That error is usually happening with the shared version when an application has not been properly deployed.
What do you mean shared? is that as opposed to the static build i've been trying to do?
Sorry but I don't understand how your post is meant to help me.
The application hasn't been 'deployed' (windeployqt? which i shouldn't need to do anyway because its meant to be static/standalone) yet because I'm still working on it in creator. The other plugins i need are now statically built / installed as was in an above response. The only thing that doesn't show up is the windows in "%QTDIR%\plugins\platforms" (I needed to add QT_QPA_PLATFORM_PLUGIN_PATH to windows environment variables)
ive rebuilt the 5.12 static version multiple times now with other different configs to try to get it to work and the windows plugin simply never exists in plugins\platforms\