Cannot set default app for some files (PDF, TXT...) select "always" has not effect, Complete action using keeps popping up Android 10 on Samsung s10e.

Every-time I open a PDF or TXT file I am prompted to select which app I want to open the file with.
It does not matter which app I select, the setting is never remembered, I am prompted with the same question next time I try to open the file, despite clicking "always".

Already cleared the default for all apps in Settings, problem is still there.

edit : it turns out the problem also happen for other file types like .txt or even .png files, but not for .docx
My guess is problem arises only when there is more than one app capable of handling the file type.
Among the possible apps listed for both .pdf and .txt there was Mylio (a photo manager app). Thinking this might be the root of the issue I uninstalled it and could then open .pdf or.png files straight away (after selecting "Always" once more)...

As for .txt file it still prompts me "complete action with" if I try to open it with Firefox or Amaze text editor (and select Always afterwards). but if I chose Chrome it does not prompt me anymore for some reason...

I don't know if this should be the accepted answer because this is more like a workaround as it does not work with all apps. plus I don't want to uninstall Mylio as I use it regularly.

edit : turns out that if I disable Chrome (could not uninstall it) it then works for .txt file (meaning I can chose any app, select always and it will not ask me "complete action with" again)