alt keys broken after upgrading from ubunutu 18.04 to 20.04

I recently upgraded to 20.04 LTS from 18.04 LTS and now both my left and right alt keys are not working when I try to use them for any keyboard shortcuts. I had no issues before upgrading. My keyboard is mapping hasn’t changed since the update (Macintosh UK).

Any help would be appreciated. Thanks in advance.