As of yesterday, I have had multiple instances of custom command bar buttons not working using PowerFX. Neither the visible nor onSelect properties of any of the buttons are working. The error that is being shown in Dynamics when trying to select one of them is as follows:

After some initial troubleshooting, it appears as though this issue occurs when the underlying component library is saved and published, even with no changes made. This is happening in multiple environments and tenants, But not all at this stage. Another custom button that is using JavaScript appears to be working fine, this seems to be limited to powerfx command buttons only.
Does anyone have any idea what might be causing this and what the resolution could be?