Tap dance on tap triggered when on hold is expected

[LyraelRayne]

I have the use case that I want KC_A/KC_D when I on tap A/D, and KC_LEFT/KC_RIGHT when I on hold the respective key (for use with games, where it'd be handy to have an extra 4 action keys, but still be able to move using WASD).

What happens

Currently if I set it up this way I get the following behaviour:

• I press and hold A down KC_LEFT is held (good!)
• I decide I want to start moving right, I hold D then release A during the tapping term - KC_LEFT is released. (unexpected)
• Release D - KC_D is tapped once (also unexpected)

What I expect

• I press and hold A down - KC_LEFT is held
• I press and hold D then release A during tapping term - KC_RIGHT is held. KC_LEFT has not been released yet
• I release A - KC_LEFT is released

Basically I expect the Tap Dance keys to work at the same time as one another without interfering with the other tap dances and this is not what is happening. This seems to be similar to an old (now fixed) QMK bug qmk/qmk_firmware#527 so perhaps the solution to that might also work for this?