jFiles is the culprit...
Version 1.51 (1 September 2017)
Add: MaxPrefixLengthInJSON property. This sets the cut-off length for removing prefixes, from the incoming JSON, when removePrefix is on. The default value is 4 (which includes the separator.)
This "add" makes that all my json objects now include the prefix.
I had to add:
json.RemovePrefix=1
json.MaxPrefixLengthInJSON=100
for it to work like the last version.
Regards