I have the same on my q30 and q5 pro and has existed for sometime now. It is something himedia has never attended to or fixed and they probably never will. It's a bug in himedia firmware.
The problem is related to google play store and google play services updating the default old apk's in the himedia firmware. When google play services is automatically updated and you are logged out of google play store, it is impossible to get the login page to google play store. The app keeps crashing.
The only way to fix is to uninstall the google play services update in the app settings (top right hand corner I think) and then the google play store app works again.
Unfortunately you cannot stop google play services from updating automatically, even being logged out of the google play store somehow google play services app updates itself. So if you are logged out of play store you will have to go through the whole rigmarole of uninstalling google play services updates to access the play store again.