Sorry for the late response.
I checked my process, but unfortunately wasn't able to find any "extra" items on the request process.
I have been performing some testing and I have found what "triggers" the error.
If no service level is defined on the request, it seems to open correctly as expected.
Any ideas if it is still related with the 1st assumption?
Thanks in advance,
This error seems to be resolved in 2017.3 Service Desk version.