@rfc2822 Thank you for following up. The best way I could find to try to convey the feedback was to use their chat feature on their web page which unfortunately means I have no record of the conversation.
The representative tried to inform me about all the things I already knew, like how they supported so many calendars, how I am the only person to raise the issue etc., but after repeating myself a few times said they would provide the information to the developers.
I asked if I would get advised when/if the developers looked/fixed it but was told probably not.
So for now I can view the calendar in all I use except on my Android phone. That’s OK as not a vital thing, just frustrating.
If needed, this item can be closed. Thanks again.