I have lost my right-click Explorer integration; shell integration ("add run Sandboxed...") is enabled. I know I have had this problem in the past and I have searched for a solution to no avail. I downgraded to 1.15.0, but no joy. I haven't yet tried a full uninstall/re-install. AVG doesn't like the 15.1 installer, says sandboxie-plus-x64-v1.15.1.tmp is infected with FileRepMalware [Misc] so I'll keep 15.0 for now.
If you're using Windows 11, try restarting the system and then toggling the integration option off and on again. Sandboxie-Plus > Options > Global Settings > Shell Integration > Add 'Run Sandboxed' to the explorer context menu AVG = false positive
I had already tried toggling the integration. In the end, I had to uninstall and reinstall, and even then I had to toggle the integration before it would work. All ok now though.