Sub-layers not visible/selectable

[PascalVanhees]

Hi!

First of all, I just wanted to say, I'm a very basic user and by far a 'specialist' in this. So I probably will not use the correct terms. But I hope my question is clear. If not, please let me know!

Our local GIS-person made a few maps for our employees to work with. He added a webservice of a Flemish map called 'GRB'. It contains a lot of sub-layers like (property)boundaries, (main)buildings, streets, rivers etc..
We used 'Collector app', in which we could select each one of these sublayers. Collector is not available any more, but now its 'Field Maps'. In that app, it is not longer possible to select these different sub-layers, which is annoying, to say the least. 

Anyone have a sollution for this?  

[PascalVanhees]

Here two screenshots. 

Left side is from 'Collector', right side is from 'Field Maps'. 
(Its in Dutch) The layer 'Perceellabels en gebouwen GRB service'with (collector) and without its sub-layers (FieldMaps)....