“Select From Server” problems

I am getting the same problem as reported in an earlier topic. When I first used the “Select from server” option, it worked properly. However, now, on either Safari and Firefox, the dialog displays and after a few seconds loads two folders “undefined” under Home. At the same time, in Safari, a Mac notification is displayed: saying that “Error! Session Expired. Try refreshing page.” When I display the Web Console, the messages are displayed:

Notification granted
Failed to load resource: the server responded with a status of 404 () [looking for (mywebsite)/wp_admin/%7B%7Bicon]
WebSocket connection to ‘wss://public-api.wordpress.com/pinghub/wpcom/me/newest-note-data’ failed: Unexpected response code: 403

No files are displayed, the throbber keeps throbbing and the count of messages about Websocket problems is incremented once every 2 minutes or so.

When I attempt to use it in Firefox, the messages are different, but the results are the same.

This page uses the non standard property “zoom”. Consider using calc() in the relevant property values, or using “transform” along with “transform-origin: 0 0”.
Notification: default
The Notification permission may only be requested from inside a short running user-generated event handler.
The connection to wss://public-api.wordpress.com/pinghub/wpcom/me/newest-note-data was interrupted while the page was loading.

I have tried logging out of my website and logging back in again but that makes no difference. Maybe the authentication problem is with accessing the WordPress REST API after an initial login times out.

I have been delaying replying because just before your reply it started working again. It now works properly in both Safari and Firefox, so I have no idea what has changed. If it stops working again, I will follow it up.

Thanks for your time.