Yes, the lock miter is fussy to set up. It's
REALLY sensitive to material thickness - it has to be within 1/64" or better in consistency. Then, it references off of the inside face of the corner- which can be counterintuitive. Once you've got those things sorted it's pretty foolproof. I've had much better luck using a power feed than hand feeding too.
Not sure if this will work, but here's a bit of video where I'm doing a table top edge (in European Oak) with a lock mitre. It's a hexagonal top, so them corners are at 60º.
Lock Mitre Table Top Edge from C Freeborn on Vimeo.
I've used the solid wood trick with veneered work too. Great technique. I do a fair amount of custom veneering so I'll frequently edgeband before I lay up the veneer to get the same effect.