I couldn't perform any operations on S3 buckets due to this issue. If you are going to be in the business of building a client on top of a third-party API with no defined long-term protocol or RFC, you should be in the business of providing ongoing support for it too.

Transmit spent so long developing v5 and didn't provide this (important) update to any v4 users even when it was present for around 2-3 years.

Let's hope they provide better support, for all the other new services they have added, going forward.