I’ve got a conflict between Events Calendar PRO and WYSIJA (newsletter/subscription plugin).
The WYSIJA administration screens will not display while EC PRO is active. Seems it’s *just* PRO and not Events Calendar basic. WYSIJA is still sending out post updates while PRO is active – so it’s just the admin screens.
I recently upgraded to PRO from basic and had the same problem with *ALL* admin screens until I disabled both PRO and basic and re-enabled them in sequence.
Short term, I can disable PRO while updating WYSIJA. Long term, it’s a real PITA.