Register a Workspace in Microsoft Remote Desktop for Mac

Question

I am having problems getting a workspace added to Microsoft Remote Desktop (for Mac). Using it on a Mac Pro with macOS Sonoma 14.0, with Microsoft Remote Desktop (10.9.4 (2161)). This hasn't worked for a while. I've tried completely removing the app and deleting the associated files and caches. Then starting over from the beginning, but it isn't helping.

The workspace adds just fine in a windows environment. Logging on the mac shows the following:

E|2023-10-23 10:42:05.3310 -05:00|:0 {eafe417e-6cd2-4e45-9ed6-d44a9ea90000} <0x70000e971000> WORKSPACES(ERR): [4F7CCEE5-65ED-45A0-A73A-CAA311BF407C] requestId: 0, invalid http response state: 0
    /Users/runner/work/1/s/source/workspaces/libworkspaces/workspaces/workspaces_http_channel_pool.cpp(559): OnClosed()
E|2023-10-23 10:42:05.3320 -05:00|:0 {eafe417e-6cd2-4e45-9ed6-d44a9ea90000} <0x70000e971000> WORKSPACES(ERR): [4F7CCEE5-65ED-45A0-A73A-CAA311BF407C] Workspace load failed PrematureDisconnect(17)
    /Users/runner/work/1/s/source/workspaces/libworkspaces/workspaces/workspaces_downloader.cpp(909): OnLoadFailed()
E|2023-10-23 10:42:05.3320 -05:00|:0 {eafe417e-6cd2-4e45-9ed6-d44a9ea90000} <0x70000e971000> WORKSPACES(ERR): [4F7CCEE5-65ED-45A0-A73A-CAA311BF407C] An error occurred before any resources were downloaded PrematureDisconnect(17)
    /Users/runner/work/1/s/source/workspaces/libworkspaces/workspaces/workspaces_downloader.cpp(569): OnError()
E|2023-10-23 10:42:05.3320 -05:00|:0 {eafe417e-6cd2-4e45-9ed6-d44a9ea90000} <0x70000e971000> WORKSPACES(ERR): [4F7CCEE5-65ED-45A0-A73A-CAA311BF407C] m_spWorkspacesDiagnostics is null. cannot send Final event
    /Users/runner/work/1/s/source/workspaces/libworkspaces/workspaces/workspaces_downloader.cpp(926): OnLoadFailed()
E|2023-10-23 10:42:05.3320 -05:00|:0 {eafe417e-6cd2-4e45-9ed6-d44a9ea90000} <0x70000e971000> WORKSPACES(ERR): [4F7CCEE5-65ED-45A0-A73A-CAA311BF407C] Workspace (4F7CCEE5-65ED-45A0-A73A-CAA311BF407C) downloaded with error:UserCancelled.
    /Users/runner/work/1/s/source/workspaces/libworkspaces/workspaces/workspaces_subscriber.cpp(772): OnCompleted()
E|2023-10-23 10:42:14.4360 -05:00|FileLoggingWindowController.swift:194 Logging to file finished!!