TreeTable search/filter works not correct

Hello colleagues, I have problems with treeTable search/filter. first I want to mention that I have read about treeTable filter and "operationMode: 'Client', useServersideApplicationFilters: false" options. But from debugging i can see that my default search should work also without those options, the only thing is, that in request i have "HIERARCHY_LEVEL eq 0" this gives me wrong results:

Maybe somehow I can remove it ? Maybe there is some setting?