There is currently a problem in the way Appsheet returns access keys to Zapier. Instead of returning the new API Access Key for each application, we are still returning the old Application Access Key. If you call the REST API from Zapier, please do not rotate you API Access Key until we release a fix for this problem.
We plan to release a fix for this problem in the next day or two. I will post an update here in the community when we have done this.