I have done quite a bit more troubleshooting on this and can confirm that the S3 restore problem occurs before CWP ever attempts to connect to the S3 server.
My setup is AlmaLinux 9.8 using the New Backup (beta) system. Local restore is working now, but S3 restore still does not populate the Frequency, Backup, or User Accounts fields.
The S3 storage is a Garage S3-compatible server. Backups to it are working normally.
I verified the following:
* The backup archives are present in the S3 bucket in the expected structure, for example:
`full/daily/Sunday/accounts/user.tar.gz`
* Using the same endpoint, bucket, region, access key and secret key stored in CWP's backup configuration, `aws s3 ls` successfully lists the bucket, directories and account backup files.
* CWP itself successfully uploads backups to this same S3 bucket.
* The CWP AJAX request for `searchbackupaccount` returns HTTP 200, but the response is only 5 bytes when S3 is selected. The equivalent Local request returns 82 bytes and the restore selections populate normally.
* There are no corresponding errors recorded in the CWP backup `errors` or `restore` SQLite tables.
* I ran tcpdump while selecting the S3 restore source. CWP made no connection at all to the configured S3 server.
* I then traced the CWP PHP-FPM process. During the S3 restore request CWP reads `/usr/local/cwp/.conf/backup_config.sqlite` and checks that the AWS CLI is installed with `which aws`.
* CWP finds `/usr/bin/aws`, but it never executes an `aws` command after that check.
* Since no AWS command is executed and no network connection is made to the S3 server, the restore code appears to stop locally before it ever attempts to enumerate the S3 bucket.
I also compared the working Local backup configuration with the S3 configuration and tested the few potentially relevant differences. Changing `S3_PATH` from an empty value to the database default of `0` made no difference. I also tested `DEFAULUSERBACKUP=0` instead of `1`, with no difference. Both values were restored to their original settings after testing.
At this point I don't believe this is an S3 credentials, permissions, endpoint, network, or AWS CLI problem. All of those work when tested directly, and CWP is successfully writing backups to the same bucket.
It appears that the New Backup (beta) S3 restore discovery code is returning before it ever attempts to access S3.
Hopefully this additional information will help locate the problem.