You are correct in that it was about the shield being energy. That issue also extended to other materials.
So I fixed that, and did some stuff.
1) Syntax in helpfile fixed to just 'deflect'. 2) Material issues fixed
There now will always be echoes. I also added in a few special things: When you deflect an energy shield with an energy mace, a water shield with a water mace. I didn't go any deeper than that since I was mainly filling in missing variables.
But maybe at some point (perhaps a Santa Umishuli wish) I'll fill out all the material match-ups.
Short version - it's fixed and echoes should always happen now.