Can't open attachment in appropriate application from Thunderbird

When I try to open a PDF file from an attachment in an email in Thunderbird, I only get a few applications and none of them are appropriate to open PDF files:

When I save the file to my HD, it opens by default with the correct application (Document Viewer) and I can also choose a lot of other applications:

Edit: When I go to Preferences -> Attachments -> Incoming I don't see any filetypes that I can set any action for:

Why can't I open this file with the correct application from Thunderbird? How to fix this?

Solution 1:

Did you install thunderbird via snap? I had the same issue.

After deleting the snap instance and reinstalling via

apt-get install thunderbird

it worked well.

(Be aware: deleting the snap instance will automatically delete all the data, so backup your emails before doing that!)