Dont know if this helps or not, but Ring is built on BTC core 18 which changed getblocktemplate. This is from core website.
Notable changes
Mining
Calls to getblocktemplate will fail if the segwit rule is not specified. Calling getblocktemplate without segwit specified is almost certainly a misconfiguration since doing so results in lower rewards for the miner. Failed calls will produce an error message describing how to enable the segwit rule.
I found this for Litecoin:
You need to explictly declare the segwit rule:
litecoin-cli getblocktemplate '{"rules":["segwit"]}'