Had a couple times where AI goes for melee, Machine Strike flashes but nothing happens. Usually followed by Hydraulic Slam and ending their turn.
Also, have had multiple cases where characters engaged in melee can't do anything on their turn: disengage, attack, use skills, etc. They have AP/MP available. Usually on stairs or uneven terrain and multiple characters engaged. Acted kind of like the issue if you end your turn right next to where another character will deploy and when they pop in you're both stuck (ie, overlapping character circles).