We've been researching this issue, and the results have varied. I tried it on a different PC and was able to attack without any problems. Please submit a ticket if you encounter this issue. If you are unable to drop troops and can leave combat or manipulate the Troop Tray, please refer to this as your strike attack being locked or frozen. This is to distinguish it from those who claim they're running into a 'crash', as that may be a different issue entirely.
This occurs to me as well, I constantly have somewhere between 1-3 daily strike attacks have this problem, and this happening intermittently for war (though not as often on the latter -- it is mostly really bad for strikes, where I basically lose about half my daily attacks because of it).
Add me to that list as well when using my Domi Worlds accounts. Not only are troops unable to be deployed, the map itself is frozen and you cannot navigate around the base to be attacked. It is locked into the opening view only. Just had it happen again and came here to see if it had been reported. Will generate ticket next time as asked
ETA** This only happens for me on STRIKE missions. All other regular attacks, everything works as it should.