Odd one this. I am on a Mac with Catalina. I go to the file menu but LibreOffice cannot see anything. The little coloured circle rotates for about half a minute and then stops. Why is it not seeing my files?
This is happening to me, too.
This issue disappeared after I restarted the app, restarted my firewall, and tried opening the app in safe mode. Not sure which one of those three things did it, but I suspect it was going into safe mode (where the problem still occurred) and then opening it up normally. The firewall would be the last choice, as I don’t think it needs Internet access just to open files!
I can vouch for the safe mode solution. I did have to learn it the hard way, though, because I didn’t know/remember that LibreOffice has a safe mode restart option (in the help menu), so I actually restarted my entire Mac(!) in safe mode, ran LO, closed it, restarted the Mac normally and – boom – no luck. So I dropped some keywords into the search field here and – boom – nothing. So I went to the help menu in LO hoping to find a link to one-on-one support and – boom – said “restart in safe mode” option. It was smooth sailing from there, per hkottman’s answer circa Nov 2019.
You might like to look at this question 279603 especially Caudel’s answer about
clicking on "Use LibreOffice dialogs" in Preferences -> General -> Open/Save Dialogs