Trados 2017: Problem with custom filetype since CU18

Hello,

We have a problem with the new cumulative update 18 regarding the use of our custom filetype. They are not anymore displayed in the filetype list and can't be found in the "additional filetypes available" link. In the same project opened in 2017, CU17, the file types are displayed.

I already had this problem with Studio 2019 CU4 and found this information by Tom Imhof:

https://community.sdl.com/developers-more/developers/language-developers/f/sdk_qa/27536/cu4-of-studio-2019---creating-the-project-object-leads-to-exception-the-requested-service-is-not-available-sdl-desktop-platform-services-iusersettingsservice/87662#87662 . Here, there's a notice by  about a "configuration issue in CU 4" and "SimpleInjector". With CU5, everything works again, so the problem has been found and solved.

The problem in Studio 2017/CU18 may be related.

Have you already encountered it? Do you need more information?

Thank you

Sébastien Desautel