seem to be still a open topic in backlog list to fix? Tried to...
1. adding an existing instant flow to a new solution = does not work, flow is not listed
2. changing an existing instant flow (delete existing instant trigger and replace with an "PowerApps V2 trigger" = does not work, flow is not listed
3. creating a new instant flow via "add" inside a solution = does work!
4. "ZIP Export" of an a instant flow is only available via make.powerautomate.com but not via make.powerapps.com