Subscribed read-only calendar not updating

Hi there,

I imported my garmin connect calendar into Nextcloud (as well as phone using ICSx5). When I added it, it correctly imported the events.
the problem is, it doesn’t update - as new events are added into the Garmin calendar, they correctly show on my phone (via ICSx so it’s not a garmin problem), but not in NextCloud. I do have crontab set up (every 15 mins).

Is it a bug? Is there a workaround or come config setting? I’d like it to update periodically…