When using the MULTI compiler option --brief_diagnostics the warnings plugin reports only one warning that contains the whole content. If there are many warnings the warnings overviews are missing completely (probably something crashes?). The main difference is that the warnings are single line warnings and they contain the column

Regular output:

"D:\jenkins\src\MyFile.cpp", line 42: warning #381-D: extra ";" ignored

...

Brief diagnostics:

"D:\jenkins\src\MyFile.cpp", line 42 *(col. 58)*: warning #381-D: extra ";" ignored