What finally worked for me, after trying (and failing) with all the other suggestions, was downloading the offline installer and installing from the root C: drive.

Logitech Options + and Flow were working just fine until the last update. I use flow from a Windows 11 PC to a MAC. It now will continually when I go from the PC to the MAC and want to copy and paste something, the MAC will start spinning and then the Windows PC will show backend connection problems, and then flow will not work at all. It is infuriating, especially as it has been working for YEARS, and I did not change a thing on my PC and have tried every fix posted online.