Missing with red dotted line when saving files as PDF under Photoshop

This problem can be caused by layer visibility or PDF settings. Make sure the red dotted line layer is visible and select "Preserve Photoshop Editing Capabilities" when saving as PDF. Also, try exporting to PDF via "Export As" instead. If the problem persists, consider software updates or contact Adobe Support for assistance.

To rasterize the red dotted lines layer, you can follow these steps:

1.
Select the layer that contains the red dotted lines in the Layers panel. You can tell if it is a vector layer by looking for a small icon of a square with a pen on it at the bottom right corner of the layer thumbnail.
2.
Right-click on the layer and choose Rasterize Layer from the menu that appears. Alternatively, you can go to Layer > Rasterize > Layer from the top menu bar.
3.
You will see that the layer thumbnail changes and the vector icon disappears. This means that the layer is now rasterized and you can use any tool or effect on it.
4.
To export your document as a PDF file, go to File > Save As and choose Photoshop PDF from the Format drop-down menu. Click Save and then choose the settings you want for your PDF file in the dialog box that appears. Click Save PDF and your file will be created

Rastrise the red dotted lines layer and The lines will be visible on pdf file.