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 mapping hasn't changed since the update (Macintosh UK).
Any help would be greatly appreciated.
Edit updated with xmodmap output
xmodmap: up to 4 keys per modifier, (keycodes in parentheses): shift Shift_L (0x32), Shift_R (0x3e) lock Caps_Lock (0x42) control Control_L (0x25), Control_R (0x69) mod1 Alt_L (0xcc), Meta_L (0xcd) mod2 Num_Lock (0x4d) mod3 mod4 Super_L (0x85), Super_R (0x86), Super_L (0xce), Hyper_L (0xcf) mod5 ISO_Level3_Shift (0x5c), Mode_switch (0xcb)