I've created a BSM only with one service from one node. Now the BSM goes down because the service went down and the BSM changed his severity.
That's correct behaviour.
If you remove the service from this specific node (not sure if before or after BSM severity changed) and you click on (in my case) the red BSM on the starting page I will get an error like the screenshot shows.
The karaf.log only brings binary lookalike content.