https://github.com/CiscoDevNet/webexteamssdk/blob/49a0a0d07d8d7c11abdf599396c814455261cc76/webexteamssdk/api/messages.py#L244

https://github.com/CiscoDevNet/webexteamssdk/blob/49a0a0d07d8d7c11abdf599396c814455261cc76/webexteamssdk/api/messages.py#L259-L265

In the attachments processing code, an extra s was added on to attachments on line 264.

This checks whether the attachment list is an instance of an AdaptiveCard, which it never will be due to the earlier type check on line 244, rather than checking whether the attachment item is an instance of the AdaptiveCard and makes it impossible to send AdaptiveCards using the intended message.create() functionality.

This can be worked around by importing make_attachment from webexteamssdk.utils and calling that on the card before passing it to messages.create()