https://minecraft.gamepedia.com/Trident says Loyalty and Channeling are mutually exclusive from Riptide, but not from each other. so, i take that as Loyalty and riptide cannot be together... I put both on a trident (L and R).. is this correct? or am I just really needing sleep?
To my knowledge, loyalty and riptide can be on a trident at the same time but once you put both on you can no longer throw it due to riptide.
As far as I can tell this is due to the fact that we allow non-vanilla enchants to be put on items by the server (eff7s for example). I've tested this thoroughly and it seems that putting riptide on a trident will override everything else, and it will work like a trident with just riptide on it no matter what other enchants it has.