Invalid file name error when applying retention label

Hi there,

I have recently created and published some retention labels for a tenant.

After publishing them, I applied them to document libraries and folders just fine.

A few days later, when I try to apply or remove a label to a folder or document, I am met with an error. (seen in the attached image)

After clicking the new label again a second time, I'm still given the error, but the change appears to take affect.

This does not happen when applying a label directly to a document library, from within the library settings.

This happens on all sites.

Any help here would be greatly appreciated.

Thanks.