Roofshield isn't a VCL. It's breather membrane. It's hard to say what the problem is from a photo but there are signs of white spores in one of the pictures and this is a sure sign of condensation. The condensation may be forming from the water that has saturated the battens etc and hips may also be leaking. It would be interesting to see under the roofshield because there maybe another underlay.It looks to me (could be wrong) that the problem is the missing courses of tiles. This has caused the staining; rain water dripping straight through between the tiles. The VCL is fine ("Roofshield") and has been the only thing keeping the rain out.
Exactly half the tiles are missing. Unbelievable - but it has been done before. Not as a rip-off just sheer ignorance/inexperience, probably a first time DIYer
A vapour control layer needs to be as close possible to the ceiling below.
PS. 40 Years in roof surveying.