This is intended. It works the same regardless of what faction does it.
Pios cannot help Grenadiers with bunkers
Sturm Pios cannot help Volks with Bunkers
Rear Echelon cannot help Rifles with bunkers
Same applies to Tommies
Edit:
Unless they've changed something
-
#Steam AliasWL%Streak
- 1.829222.789+35
- 2.34857.859+13
- 3.587233.716+3
- 4.1095612.641+19
- 5.882398.689+4
- 6.280162.633+8
- 7.997646.607+1
- 8.379114.769+1
- 9.300113.726-1
- 10.717439.620+1