Then it isn't marked as installed
OK. It's a bug then. If you can, please check with trunk if the same issue exists, so I can fix it. Thanks.
PS: I did run a quick test(Lazarus trunk).
1. Installed Indy via OPM
2. Uninstall it via "Install/Uninstall Packages"
3. Restart IDE-->Indy is marked as uninstalled in OPM
then
1. Install Indy via OPM again
2. Uninstall Indy via OPM
3. Restart IDE-->Indy is marked as uninstalled in OPM
In trunk everything seems to work fine, but you can run a few test too if you like.