This comes up in the "All Together" scenario, where you change trains at Bochum. You take over the second train and..... nothing. The throttle has no effect. No, the brake interlock isn't on; no, the brake key isn't locked; no, this isn't the old "stuck brakes" issue (BC pressure is zero). The train rolls due to gravity- but the throttle has no effect at all. No juice. (And, no, cycling the MCB isn't a fix: that disables the whole train irecoverably)
All right- it's deff. a bug (it shouldn't happen, especially taking over a hot train), but I found a workaround. Don't touch the MCB - that's fatal - just lower and raise the panto. There will be about a 60 second delay until you have power back. At this point you get the red lockout box; move the throttle than pull it back to Off to make that go away. From here you're good to go -behind schedule, but rolling. (Also, if you have AFB on you have to cycle the on/off switch to get it back).
I played this last night on XSX to try out. I had zero issues and just followed all instructions. I drove both trains without AFB. I never had to cycle the pantograph or MCBs. Everything worked just fine.
Me three on PS4 & TSW2 and with AFB. Drove that scenario again (in order to figure some help) but without any troubles or hiccups. Just the heavy rain sure makes braking a lot ´funnier´.