Resistance suddenly too hard in the middle of training

[giovannibavutti]

ELITE DIRETO 2019, PC WINDOWS10, ANT+, TRAINER ROAD

In the middle of the training, sometimes pedalling get so hard I just can't move the cranck.
Power value is properly shown within trainerroad: for example, yesterday the issue happened at 280W (FTP 347W).

Any opinions or suggestions to solve?

[marass]

Same here, happens from time to time on different occasions while doing ERG workouts on ZWIFT. '

DIRETO 2018, macOS, ANT+.

Marek