hmmm - I am backing up more than 20 machines with restic to wasabi for nearly two years now. Never had any problems. Also with the new 0.10.0 everything works fine.
Regarding the problem of the threadstarter, the only diference to my setup is that I have the region in the bucket url. Example:
export RESTIC_REPOSITORY="s3:https://s3.eu-central-1.wasabisys.com/bucketname"
So I am not sure if you can access your bucket just with s3.wasabisys…