Wacom tablet issues in Illustrator CC

[default74748bt2iisb]

I' having troubles using my Wacom Intuos tablet in Illustrator CC. When drawing with the pencil tool, the path doesnt want to close easily. No matter what settings I put for the option "close path within __" . Even though I wait for the littl O sign to appear indicating the path will close, it doesnt most of times and have to repat the action multiple times until miraculously it closes. Also the preview of the line I draw is not accurate and shows straight lines (see screen shot). I hope someone could help as I have tried to reach wacom and they tried evrything on their end. I do not have this issue on my laptop wich uses a different Illustrator and different OS so I'm thinking it could be an icompatbility with my imac's illustrator or OS. Here are some infos 

OS: Mojave 10.14.6

illustrator cc: 25.4.6

I'm inluding some screen shot of the shape I'm getting when the path doesnt want to close. And also my pencil settings. and teh preview problem

Attached is a picture showing the kind of shape I'm getting without a closed path 

tablet: Wacom Intuos

[Laura Coyle.]

I don't have a Wacom tablet to test this myself, but I'm curious if you are having the same problem when you draw with a mouse. If it works with the mouse, then it's a problem with the tablet/driver. I've had problems with an older tablet not working well with Illustrator v25. On your laptop where everything is working, are the OS and Illustrator up to date - maybe that's why it's working there? On your desktop computer, have you reset preferences to clear out anything corrupted? Here's a help article: https://helpx.adobe.com/illustrator/kb/troubleshoot-preference-issues.html

[default74748bt2iisb]

Thank you so much for trying to help! I have tried with the mouse as you suggested and the jagged preview is still a problem but the path closes normally which is my main concern with my tablet. I also have an older wacom tablet that I have tried and it does the same closing path problem. The illustrator on my laptop is not up to date because I am limited by an older OS (Sierra) but my tablet works perfectly there. But the illustrator on my newer imac where I have the problem is up to date with a Mojave OS. With the wacom technician we removed the driver completely and resinstalled it without success in fixing the issue. I am really desperate to find a solution as this problem limits me so much in my work and I am losing too much time. I tried buying another tablet would fix the issue but no... Any other suggestion is really appreciated. thanks!