me and a friend have been testing entrenchment on multiplayer - and we have tried this on many multiplayer maps, and this is definetly not a random bug. whenever we try to upgrade a starbase of any race, it shows the assignments as waiting, and never actually completes them. it is very frustrating because it does'nt seem to affect the AI, who can upgrade at their will.
it defeats the point of starbases, meaning they are weak, cannot attack, and are simply turrets with little more power.