The monitoring graphs stopped on Apr 11, which is a Thursday, which points to maintenance window - possible the updates broke something.
What I found is that rrdcached.service was going in a loop, failing every minute or so and restarting itself. I couldn't find what the issue is, no help in the logs. In the end I changed vendor from SUSE to obs and installed a newer version from our NPI repo. The graphs are getting data now.
About the "you did an active check on this service - please disable active checks" message, it seems all hosts that use passive instead active checks have that message, probably from when they were added for the first time. I think is safe to ignore it. As you can see now from the graphs, the client sends to monitoring server the data successfully , i.e. passive checks.
For the link where you're missing permissions, that's the Icinga config section for this host, that is managed by Infra and where I don't think you should have permissions. Please let me know if you thing otherwise (via the infra ticket).
Cheers
Robert