Mapping X-Box One LB to digital L

[udqm]

I'm playing Super Smash Bros. Melee using an X-Box One controller connected via USB with Dolphin built from source (commit 828dc0f204841edac628d1cb5daf72c7ceca4b9f) on Debian Linux. When I map LB ("Button 4") to L as pictured, it does nothing in-game. I have RB mapped to Z and that works fine, and clearly Dolphin registers when I press LB because that's how I configured this in the first place. But pressing LB just does nothing in-game. I've also tried getting rid of the L-Analog and R-Analog mappings to no avail. Am I doing something wrong?

[JosJuice]

You should map LB to both L and L-Analog at the same time.

[udqm]

You should map LB to both L and L-Analog at the same time.

I was hoping to keep the left trigger mapped to L-Analog. Is that not possible?

[udqm]

I just discovered that even with L-Analog mapped to the analog trigger, LB works as long as I set Threshold to anything less than 100%. I'm surprised Threshold matters for a non-analog button, but anyway problem solved!