fiware-service in Orion 2.2.0

Yes, you are right, but I tried with a Orion VM in FIWARE Lab (1.3.0 and 2.0.0next) and both Orion stored data in to orion-vehicles collections. I installed manually Orion 2.2.0 on Centos 7 and I have only collection: orion, with fiware-service: vehicles. Probably it's my fault in the installation.

you need to execute a command `show databases` and see how many orion-xxx are

Yes, I'm using show databases command and also a mongo client to connect on mongo instance (after open port). In my 2.2.0 instance I can see only after '> show databases': admin 0.000GB config 0.000GB local 0.000GB orion 0.000GB

The only difference is the version of mongo. I'm using 4.0.9 for Orion 2.2.0, instead Orion 2.0.0next uses 3.6.9

probably, try

I don't agree with the recommendation on not using servicepath. Service path is an additional level of grouping that you can use if service is not enough. The problem of "not finding entities" would happen exactly the same for service so the rationale of the recomendation is not clear to me.