Nextcloud-Mail app: Error on update signature above quote

Hi all,
I get a 405 error when trying to update the signature to appear above quote in Mail app. The checkbox is blinking and I can see numerous errors in browser log:

PATCH https://cloud.xxx.com/nextcloud/apps/mail/api/accounts/3 405

ConsoleLogger.js:41 [ERROR] mail: could not update signature above quote 
{app: 'mail', uid: '2linfo', e: Error: Request failed with status code 405
    at t.exports (https://cloud.xxx.com/nex…}
app: "mail"
e: Error: Request failed with status code 405 at t.exports (https://cloud.xxx.com/nextcloud/apps/mail/js/mail.js?v=2a936990-8:277:14917) at t.exports (https://cloud.xxx.com/nextcloud/apps/mail/js/mail.js?v=2a936990-8:343:19199) at XMLHttpRequest.w (https://cloud.xxx.com/nextcloud/apps/mail/js/mail.js?v=2a936990-8:277:13307)
uid: "2linfo"
[[Prototype]]: Object

Updating the signature works well (PUT https://cloud.xxx.com/nextcloud/apps/mail/api/accounts/3/signature OK)

Nextcloud 22.2.3
Mail 1.11.6