A small bunch of people are having power related issues as well as the odd possible bluetooth issue. I would say that Zwift are having a small run of bluetooth issues over the past month or so (as if the sensivity has been reduced hence people are having disconnects). See this post from Zwift but this may be red herring.
The only consistent issue with V5’s seems to be gradient feeling reversed/lagging, not working sometimes. Having a read of this thread to see if symptoms are similar. A post (#15’ish) offers how to downgrade firmware, but I would caution doing that if the symptoms in the thread dont match yours. Ask Wahoo if you should do this.
Regarding the spindown, even though you shouldnt have to do one on a V5, if Wahoo are suggesting it then make sure you only use the Wahoo app, and I’d power reset the Kickr to make sure any existing bluetooth connections arent active. Dont use the spindown feature in Zwift. Also if you run Garmin Connect on a phone, make sure you have fully closed that.
Factory spindown instructions here