S3 Bucket Tagging with boto3 works in some regions but not others?

Does anyone know if there are limitations with boto3 working in some regions but not others?

I'm tagging S3 buckets with a python script using boto3. I'm running the script in us-east-1 region, and I've tried running it in several other regions. The script runs fine, except when processing buckets in regions like ap-east-1, af-south-1, me-south-1. For that sake of clarity, I'll call these regions the "outcast" regions. It lists the buckets but does not perform any action, such as printing a notice that "bucket XYZ already has the tag", or "tagging bucket XYZ with tag <some key>: <some value>". It tags buckets with no problems in ap-southeast-2, us-xxxxx-xx, eu-xxxx-xx, and ca-central-1 regions. I've checked my account access to these regions, and I have access to all of the regions including the "outcast" regions. The script lists all the buckets and iterates through the list. It skips buckets that are already tagged and tags buckets that are not tagged, but when it gets to any of the buckets in the outcast regions, it prints the message "Processing Bucket XYZ" and then simply moves on to the next bucket in the list without reporting whether or not that bucket has the tags. I've run the script in some of outcast regions as a test and saw the same behavior there. I've also noticed that the AWS Resource Groups and Tagging Editor does not list buckets in the "Outcast" regions.