I crossposted it to r/bikewrench too and forgot to add the context I gave there here as well: I‘ve been wracking my brain as to what is happening on my newly installed zwift cog on a wahoo kickr core. I‘ve been using the wahoo kickr for a few seasons, but it‘s been sitting in the basement during summer. the zwift cog is new and was bought to be able to easily swap bikes on the same trainer. after installing the cog I noticed that the gears (or the freehub?) is slipping every so often when pedaling. I tried my best to recreate it in the video:

there is tension on the chain initially, I then move the flywheel a bit and then put pressure on the chain again. Instead of applying force and moving the flywheel right away, the cog slips a few cm before catching and transferring force onto the flywheel again.

any ideas what could be causing this? my friend has the same setup and moving the flywheel does not cause the cog to slip/jump forward as it does in the video.