Well, if you only started using Zwift, a reasonable question to ask is if you signed up for subscription and your first month has been paid? Normally, you have a trial period (which is either 7 or 14 days, I can’t remember), after which you move to a “free” mode in which you get only 25 km per month. If you are out of your monthly allowance, you will be able to login, but your avatar would not move.
The second possibility is that you might have connected your power sensor to the Wahoo app and forgot to disconnect it. It is very rare, especially with older bluetooth devices, that they can talk to two different applications at the same time. If it is connected to Wahoo app, it probably would not connect to Zwift, even if they run on the same device.
The third possibility, check if there is a newer version of firmware for your trainer. Small changes to communications protocols can mess up with the connectivity.