Designer doesn't notice that runtime started

Setup: Windows 10, CloverDX Designer 5.4.0

When Designer starts, Runtime process seems to start correctly according to Console:

But Designer doesn't detect that it started correctly and keeps waiting for several minutes with this job:

After several minutes, this error window opens:

For a while I was able to start Runtime correctly by manual start, but now even that doesn't help. I can't use Runtime now.

Log of runtime collected after Designer reported the error window: all.log

Thread dumps, collected while the Runtime was already started but Designer was 'waiting for initialization': 

• designer.tdump
• runtime.tdump

I checked Designer log as well, but there is nothing logged related to this problem.