All versions of UiPAth.UIAutomation.Activites used with Firefox 89 do not work with the selectors in the save/open file box, so this save/open file dialog box was used for my example (I know about the download file activity, but thanks for mentioning it).
Using UiPAth.UIAutomation.Activites 21.4.3 and higher with Firefox 89 will allow you to see the problem
The initial session of firefox seems to work, so you need to close and reopen firefox 89 to see the problem / subsequent sessions don’t let you select any selectors, example:
When all selectors are not working on a firefox browser non-initial session, downgrading to UiPAth.UIAutomation.Activites 20.10.10 causes the selectors to work again, example:
There is something wrong with the way the latest UiPAth.UIAutomation.Activites communicates with Firefox 89 to cause these selector problems and I believe the firefox extension probably needs to be fixed/updated. I could test with a downgraded version of firefox, but I’m sure the lower version of firefox works as it is what I was using before for months before the update to firefox 89 broke things.