On our mono deployments JSON returned from service was cut in half.
Does not affect windows deployments.
Mono JIT compiler version 4.8.0 (Stable 184.108.40.2060/8f6d0f6 Wed Mar 15 16:18:35 UTC 2017)
Revert to 4.5.6 helped, I don’t have time to reproduce this today, sorry.
I can prepare example project tomorrow if necessary.