Foreman silently removes quotes from values of hashes in parameters when storing them and also if erb is used.
In our use case it did so from the hardware address used in an interfaces hash which makes the mac address an integer (converted from hex to binary) instead of a string resulting a misconfigured network and connection loss.
A quoted string is really a string.
Foreman and Proxy versions:
Not sure in which version it broke, but it is still broken in 2.0
Other relevant data:
Issue I created for this including my ugly workaround: Bug #29787: Foreman removes quotes from hashes in parameters - Foreman
Cross posting here as perhaps someone has a better idea or the broader audience knows a fix I did