Ok so from what I've read the same has happened to me.
The normal EV suit you get from the episode "Boldly They Rode" works absolutely fine, yet every other EV suit I get just will not activate, it's not the visuals, when I click the activate button nothing happens, the activate doesn't even get the usual white rim to show it's on, the suit doesn't show on my char' and going anywhere you need one kills me, so it's clearly not equipping.
I've reported the bug before, I've just today but a request for GM help. Alas nothing so far.
Just experienced the exact same problem on my kdf toon ( at Vlugta asteroid field) :
- have mining quest
- fly to asteroid belt
- beam down and put on EV suit
- press activate button : nothing ( also cannot exit airlock)
- put normal armor back on and then EV suit again , try again : still nothing
- flew to DS9 and bought another EV suit , still nothing
- dropped mining quest and retook it from NPC himself and then tried EV suit : nothing ....