Spaces/rclone: unable to list or copy (403 SignatureDoesNotMatch and 400 BucketName)

rclone running on Ubuntu 21. Spaces set up. Access credentials are double-checked as correct. ACL set to private

cat ~/.config/rclone/rclone.conf
[hab-sync]
type = s3
provider = DigitalOcean
env_auth = false
access_key_id = <correct_access_key>
secret_access_key = <correct_secret>
region = ""
endpoint = sfo3.digitaloceanspaces.com
acl = private

Version:

rclone v1.56.1
- os/version: ubuntu 21.04 (64 bit)
- os/kernel: 5.11.0-25-generic (x86_64)
- os/type: linux
- os/arch: amd64
- go/version: go1.16.8
- go/linking: static
- go/tags: none

Running ls:

rclone ls hab-sync:/
(nothing)

Running mkdir:

rclone -vv mkdir hab-sync:5fb225099ba3874e9767b
2021/09/21 13:16:50 DEBUG : rclone: Version "v1.56.1" starting with parameters ["rclone" "-vv" "mkdir" "hab-sync:5fb225099ba3874e9767b"]
2021/09/21 13:16:50 DEBUG : Creating backend with remote "hab-sync:5fb225099ba3874e9767b"
2021/09/21 13:16:50 DEBUG : Using config file from "/home/ac/.config/rclone/rclone.conf"
2021/09/21 13:16:50 DEBUG : S3 bucket 5fb225099ba3874e9767b: Making directory
2021/09/21 13:16:51 ERROR : Attempt 1/3 failed with 1 errors and: SignatureDoesNotMatch: 
	status code: 403, request id: , host id: 
2021/09/21 13:16:51 DEBUG : S3 bucket 5fb225099ba3874e9767b: Making directory
2021/09/21 13:16:52 ERROR : Attempt 2/3 failed with 1 errors and: SignatureDoesNotMatch: 
	status code: 403, request id: , host id: 
2021/09/21 13:16:52 DEBUG : S3 bucket 5fb225099ba3874e9767b: Making directory
2021/09/21 13:16:52 ERROR : Attempt 3/3 failed with 1 errors and: SignatureDoesNotMatch: 
	status code: 403, request id: , host id: 
2021/09/21 13:16:52 DEBUG : 4 go routines active
2021/09/21 13:16:52 Failed to mkdir: SignatureDoesNotMatch: 
	status code: 403, request id: , host id: 

Attempting to copy works oput of the blue, after erroring:

rclone copy ./engine hab-sync:smartrooms-hab-sync/5fb225099ba3874e9767b/engine
2021/09/21 13:04:23 ERROR : docker-compose.yml: Failed to copy: s3 upload: 400 Bad Request: <?xml version="1.0" encoding="UTF-8"?><Error><Code>InvalidArgument</Code><BucketName>smartrooms-hab-sync</BucketName><RequestId>tx00000000000000282786f-00614a3ac7-b55a2a5-sfo3a</RequestId><HostId>b55a2a5-sfo3a-sfo3-zg01</HostId></Error>

Then

clone -vv copy ./engine hab-sync:smartrooms-hab-sync/5fb225099ba3874e9767b/engine
2021/09/21 13:17:33 DEBUG : rclone: Version "v1.56.1" starting with parameters ["rclone" "-vv" "copy" "./engine" "hab-sync:smartrooms-hab-sync/5fb225099ba3874e9767b/engine"]
2021/09/21 13:17:33 DEBUG : Creating backend with remote "./engine"
2021/09/21 13:17:33 DEBUG : Using config file from "/home/ac/.config/rclone/rclone.conf"
2021/09/21 13:17:33 DEBUG : fs cache: renaming cache item "./engine" to be canonical "/srv/openhab/engine"
2021/09/21 13:17:33 DEBUG : Creating backend with remote "hab-sync:smartrooms-hab-sync/5fb225099ba3874e9767b/engine"
2021/09/21 13:17:33 DEBUG : S3 bucket smartrooms-hab-sync path 5fb225099ba3874e9767b/engine: Waiting for checks to finish
2021/09/21 13:17:33 DEBUG : S3 bucket smartrooms-hab-sync path 5fb225099ba3874e9767b/engine: Waiting for transfers to finish
2021/09/21 13:17:33 DEBUG : docker-compose.yml: md5 = bb9f232ef81d3af978d5a9c21a0f5ac7 OK
2021/09/21 13:17:33 INFO  : docker-compose.yml: Copied (new)
2021/09/21 13:17:33 DEBUG : prepare.sh: md5 = 3d827dfb47dc50c31989ec17cc73426d OK
2021/09/21 13:17:33 INFO  : prepare.sh: Copied (new)
2021/09/21 13:17:33 INFO  : 
Transferred:   	        978 / 978 Byte, 100%, 0 Byte/s, ETA -
Transferred:            2 / 2, 100%
Elapsed time:         0.3s

2021/09/21 13:17:33 DEBUG : 9 go routines active