Images missing in tables in HTML5 output

Hi all, am hoping someone can help solve this as I am very frustrated by this issue! I have researched this problem on this site but can find no answer that works for me. 

My problem is that random png images do not appear in my project manager or in the HTML5 output. 

This usually occurs when they are in tables.  This has happened before, and I once solved it by double clicking the image and clicking OK, then Save. This seemed to register the image’s presence, but this is not working now.

Details:

• I am using Robohelp Classic 2019.
• My files are all on the local drive.
• I have tried deleting the CPD file from File Explorer and restarting/regenerating project
• I have checked the box under Options which deletes the CPD file automatically
• I've looked at the HTML code and copied rows/cells from the same table where the images are showing.
• The images are inserted by selecting Insert Image and selecting an image.
• When I insert the rogue image elsewhere in the project and save, it appears in the Project Manager and in the output. I've tried applying a condition to the "extra" image so that it doesn't appear in the output, but when I do this, the image in the proper place also does not appear.
• There is nothing special or different about the images which are not appearing - they are just small png files.
• Am attaching the row of this table with the problem. Here, the first and third images do not show, the second and fourth do.

<td style="vertical-align: top;"><p style="text-align: center;"><br />
		<span><a href="Configure_Network_Connections.htm" id="a2111" style="color: #005baa; 
				 font-size: 14pt; text-decoration: none; ">Output Stream 
		 Parameters</a></span></p>
		<p class="TOCheading" bodytext"="" style="text-align: center; color: #005baa; 
			 font-size: 14pt;"><a href="General_Device_Management.htm"><img 
		 src="Images/Output Stream Parameters%402x.png" alt="" style="border: none;" 
		 width="100" height="100" border="0" /></a></p>
		<p class="BodyText" style="text-align: center;">Options relating 
		 to the output stream</p></td>
		<td style="vertical-align: top;"><p style="text-align: center;"><br />
		<a href="General_Device_Management.htm" id="a21111" style="color: #005baa; 
			 font-size: 14pt; text-decoration: none; ">General Device Management</a><a 
		 href="Configure_Network_Connections.htm" id="a21111" style="color: #005baa; 
		 font-size: 14pt; text-decoration: none; "> </a></p>
		<p class="TOCheading" bodytext"="" style="text-align: center; color: #005baa; 
			 font-size: 14pt;"><a href="General_Device_Management.htm"><img 
		 src="Images/Device Management%402x.png" alt="" style="border: none;" 
		 width="100" height="100" border="0" /></a></p>
		<p class="BodyText" style="text-align: center;">General encoder 
		 management</p></td>
		<td style="vertical-align: top;"><p style="text-align: center;"><br />
		<a href="Maintenance.htm" id="a21111" style="color: #005baa; font-size: 14pt; 
			 text-decoration: none; ">Device Maintenance</a><a href="Configure_Network_Connections.htm" 
		 id="a21111" style="color: #005baa; font-size: 14pt; text-decoration: none; "> 
		 </a></p>
		<p class="TOCheading" bodytext"="" style="text-align: center; color: #005baa; 
			 font-size: 14pt;"><a href="General_Device_Management.htm"><img 
		 src="Images/maintenance_icon.png" alt="" style="border: none;" 
		 width="100" height="100" border="0" /></a></p>
		<p class="BodyText" style="text-align: center;">General encoder 
		 maintenance</p></td>
		<td style="vertical-align: top;"><p style="text-align: center;"><br />
		<a href="Serial_Interface_Connection.htm" id="a2111111" style="color: #005baa; 
			 font-size: 14pt; text-decoration: none; ">Serial interface</a></p>
		<p class="TOCheading" bodytext"="" style="text-align: center; color: #005baa; 
			 font-size: 14pt;"><span style="font-size: 13pt;"><a href="Serial_Interface_Connection.htm"><img 
		 src="channel_config.png" alt="" style="border: none;" width="100" 
		 height="100" border="0" /></a></span></p>
		<p class="BodyText" style="text-align: center;">Serial interface 
		 connection details</p></td>
	</tr>
	<tr style="height: 32px;">
		<td style="vertical-align: top;"><p style="text-align: center;"><br />
		<a href="Configure_Network_Connections.htm"><img src="Images/learn_more.png" 
														 alt="" style="border: none;" 
														 width="208" height="43" 
														 border="0" /></a></p></td>
		<td style="vertical-align: top;"><p style="text-align: center;"><br />
		<a href="General_Device_Management.htm"><img src="Images/learn_more.png" 
													 alt="" style="border: none;" 
													 width="208" height="43" 
													 border="0" /></a></p></td>
		<td style="vertical-align: top;"><p style="text-align: center;"><br />
		<a href="Maintenance.htm"><img src="Images/learn_more.png" alt="" 
										 style="border: none;" width="208" 
										 height="43" border="0" /></a></p></td>
		<td style="vertical-align: top;"><p style="text-align: center;"><br />
		<a href="Serial_Interface_Connection.htm"><img src="Images/learn_more.png" 
														 alt="" style="border: none;" 
														 width="208" height="43" 
														 border="0" /></a></p></td>​

Any help greatly appreciated.

Thanks

Laura