Universal Clipboard not working between all devices (but works between some); problem appears to be with MacOS

Universal Clipboard is not functioning between MacOS and iPhone or iPad.

The feature currently works seamlessly between iPhone and iPad (i.e., both ways), and it was working between MacOS and iPhone but NOT between MacOS and iPad. Then, the action started getting hung up going from MacOS to iPhone, eventually pasting, and stopped working from iPhone to MacOS altogether (first got the pinwheel, now nothing).

Everything was working fine until earlier this week when I had issues logging into my MacBook which necessitated creating a new password. As part of that troubleshooting, I also updated my AppleID password. After both of these changes, Universal Clipboard did not immediately work but soon did (between all devices) before stopping between MacOS and iPad after about 72 hours. I should also note that strangely, after logging into MacOS via the new login info, I was prompted to unlock the disk with a password, and the kicker? My new password did not work; the old one did.

Current fix attempts: the usual googled suggestions such as making sure all devices are logged in and talking, toggling on/off handoff (across all devices), reproducing issue with a different user login (same AppleID), rebooting in safe mode (issue still not resolved), deleting and rewriting the com.apple.coreservices.activityd.plist file. For the latter, I have multiple /coreservices./ files, including a 'UASharedPasteboardProgressUI.plist' and 'useractivityd.dynamicuseractivities.plist'. Can't find any info on what those do exactly, if they can become corrupted, but I have not altered them. I also ran disk utility but forgot to save the report...fml.

Please help, Universal Clipboard is a key feature I need for work, and was a major reason I decided to spend~800 bucks more for this iPad than on something otherwise similar.