ERROR : I have enough memory but showing Insufficient storage; can't install app
Have you ever used Lucky Patcher by any chance? Sometimes orphaned .odex files can cause this glitch. If you have, follow the directions here to fix the issue. Alternatively, you can manually delete any relevant .odex files from /data/app/ - they'll be stored in the folder of the app you patched. Normally you should only have to delete .odex files relevant to the app that's giving you the install error.