Can't make a goup calendar readonly anymore with Powershell (again...)

About a year ago the command  Set-UnifiedGroup -Identity "MYGROUP" -CalendarMemberReadonly was giving problems. See this post: Can't make a goup calendar readonly anymore with Powershell - Microsoft Community Hub

This lasted from june 2023 to august 2023 and then it was fixed.

After that, aside from the error message it gave, it used to work fine. But since about a week or 2 the command is giving problems again. I get this error message:

Write-ErrorMessage : |Microsoft.Exchange.Configuration.Tasks.TaskException|We failed to update the unified group. Please try again later.

At C:\Users\some.user\AppData\Local\Temp\tmpEXO_gny3w2ea.ldk\tmpEXO_gny3w2ea.ldk.psm1:1204 char:13

+ Write-ErrorMessage $ErrorObject

+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

+ CategoryInfo : NotSpecified: (:) [Set-UnifiedGroup], TaskException

+ FullyQualifiedErrorId : [Server=DBBPR04MB7929,RequestId=<xxx>,TimeStamp=Mon, 10 Jun 2024 06:36:03 GMT],Write-ErrorMessage

Do other people get this error to? How can I fix this?

Kind regards,

Paul