Issues updating bank lists BE, CH, LU, NL, PL

Dear LittleBIC friends,

we're using the latest version of this extension, v. 1.10.0, in a civiCRM 6.12.0 environment.

Trying to update the "Available banks" lists, we encounter following issues:

BE - process runs and ends smoothly (no log entries, no information popup, loading spinner gives way properly to show result), but no. of banks remain 0 (zero). - Same for LU, NL.

CH - produces warning popup:
"Problem with CH Data Source
No bank entries could be extracted from the source for country CH. It is possible that the source is outdated. If you can rule out network issues, please report this here: https://github.com/Project60/org.project60.bic/issues."

PL - produces warning popup:
"Update Problem
An error occurred while updating the bank information:
Couldn't download CSV file
Please make sure your server is connected to the internet and try again.
If the problem persists, the source file (provided by the bank) might have been changed. In this case the 'Little BIC Extension' needs to be updated. Please check here for a newer release.
If you are already running the newest version, feel free to contact us via email or on GitHub. The sooner we know about this problem, the sooner it'll be fixed."

(To be complete: AT, DE, ES return results properly, total of 4.613 banks, which implies general network issues are ruled out.)

Any insights on how to move forward from here would be appreciated. CH banks would be a priority if time is limited.

Thanks, and best regards,
C. Weikamp.

No files or tests are named. Start by reviewing the country-specific bank update paths and merged pull requests #89, #90, and #96; reproduce the BE, CH, LU, NL, and PL updates in the reported CiviCRM 6.12.0 environment, then verify that each affected country returns bank entries without warnings.