Remarks
It seems the difference is in the "roof" info.
Buildings are shown if "roof=flat" is given, but not shown if "roof:levels 0" is given.
StreetComplete software was used for data entry, which sets "roof:levels 0" (if selected by user).
"Value should be a positive or zero integer: 0, 1, 2, etc."
Some buildings are shown as a 1-level building, however they have 11-levels (no roof). The building info contains the "11-levels" info.
Expected behavior Render as 11-level building, according to the provided info in OSM (see other buildings nearby, marked with arrows).
Map location https://streets.gl/#47.43577,19.09668,45.00,0.00,888.21
Screenshots
System information
Remarks It seems the difference is in the "roof" info. Buildings are shown if "roof=flat" is given, but not shown if "roof:levels 0" is given. StreetComplete software was used for data entry, which sets "roof:levels 0" (if selected by user). "Value should be a positive or zero integer: 0, 1, 2, etc."
See at https://wiki.openstreetmap.org/wiki/Key:roof:levels