Simple, Smart, and Secure: The next step in sharing files in Microsoft 365

This is probably not the appropriate place to post this, but I've been searching everywhere, and I don't know where else to look. Around the first of May, I started experiencing enormous issues with my file-sharing ability in OneDrive.  People who work for me could suddenly no longer access files that had been shared with them.  I re-shared and re-shared, and these people could not access their files. I finally had to purchase a Dropbox subscription because people who work for me could not get access to the files they needed. Now, I'm all scattered as I have some people working in Dropbox and some people working in OneDrive. I would love to get everybody back to OneDrive.  I've looked all through the Internet trying to figure out what is going on, but I can't find any solutions.  Does anybody have any ideas what might be going on with my OneDrive sharing abilities? Has anyone ever encountered this previously?