that _ at the end of the service name is :, for example in Nagios Tok-Izhodni L1: will create a file Tok-Izhodni_L1_.*
Removing the ":" from the name will result in chart being displayed, but that is just the same as renaming the service as I have been doing.
It would not be such a fuz, but I have to rename 2100 services, without the bulk rename tool