Zwift keeps jumping several seconds during cycle training session

When I do a training session in Zwift on my bike on the turbo trainer the timer in Zwift keeps jumping several seconds so in effect what should be for example a 50 minute session ends being a 35 minute session. I have reported this before on Zwift Support. Also during tonight’s session Zwift completely locked up. The display said there were 11 secs remaining but it was like that for about 3 or 4 minutes. It would not let me access Task Manager to end the program. I had to perform a hard reboot of my laptop. I have reinstalled Zwift and cleared the cache as suggested by Support. Has anyone else had a similar issue?

Tony Dooley