Different behavior on modifiers fall-through vs. explicitly calling out key

[dalewking]

I was noticing peculiar behavior on modifier keys where i specifically specify the modifier vs. just using _ fall through. So here is my default layer:

(defalias
    hyper (around lctl (around lalt (around lmet lsft)))

    ctl_a (tap-hold-next-release 300 a lctl)
    alt_s (tap-hold-next-release 300 s lalt)
    met_d (tap-hold-next-release 300 d lmet)
    sft_f (tap-hold-next-release 300 f lsft)
    hyp_g (tap-hold-next-release 300 g @hyper)

    hyp_h (tap-hold-next-release 300 h @hyper)
    sft_j (tap-hold-next-release 300 j rsft)
    met_k (tap-hold-next-release 300 k rmet)
    alt_l (tap-hold-next-release 300 l lalt)
    ctl_; (tap-hold-next-release 300 ; rctl)

    q_1 (tap-hold 300 q 1)
    w_2 (tap-hold 300 w 2)
    e_3 (tap-hold 300 e 3)
    r_4 (tap-hold 300 r 4)
    t_5 (tap-hold 300 t 5)
    y_6 (tap-hold 300 y 6)
    u_7 (tap-hold 300 u 7)
    i_8 (tap-hold 300 i 8)
    o_9 (tap-hold 300 o 9)
    p_0 (tap-hold 300 p 0)

    z_bs (tap-hold 300 z \\)
    x_[ (tap-hold 300 x [)
    c_{ (tap-hold 300 c {)
    v_lp (tap-hold 300 v \()
    b_- (tap-hold 300 b -)
    n_= (tap-hold 300 n =)
    m_rp (tap-hold 300 m \))
    ,_} (tap-hold 300 , })
    ._] (tap-hold 300 . ])
    /_` (tap-hold 300 / `)

    nav (tap-macro-release (tap-hold-next-release 300 spc (layer-toggle nav)) (tap-macro (layer-rem num) (layer-rem sym)))
)

(deflayer qwerty
;; ┏━━━━━━┳━━━━━━┳━━━━━━┳━━━━━━┳━━━━━━┳━━━━━━┓━━━━━━┳━━━━━━┳━━━━━━┳━━━━━━┳━━━━━━┳━━━━━━┳━━━━━━┳━━━━━━━┓
;; ┃   `  ┃   1  ┃   2  ┃   3  ┃   4  ┃   5  ┃   6  ┃   7  ┃   8  ┃   9  ┃   0  ┃   -  ┃   =  ┃ bspc  ┃
       _      _      _      _      _      _      _      _      _      _      _      _      _    bspc
;; ┣━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━┫━━━━━━━┫
;; ┃ tab  ┃   q  ┃   w  ┃   e  ┃   r  ┃   t  ┃   y  ┃   u  ┃   i  ┃   o  ┃   p  ┃   [  ┃   ]  ┃   \\  ┃
     tab    @q_1   @w_2   @e_3   @r_4   @t_5   @y_6   @u_7   @i_8   @o_9   @p_0   bspc    XX      XX
;; ┣━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━┫━━━━━━━┛
;; ┃ caps ┃   a  ┃   s  ┃   d  ┃   f  ┃   g  ┃   h  ┃   j  ┃   k  ┃   l  ┃   ;  ┃   '  ┃  ret ┃
     lctl   @ctl_a @alt_s @met_d @sft_f @hyp_g @hyp_h @sft_j @met_k @alt_l @ctl_;   '     ret
;; ┣━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━┫━━━━━━┛
;; ┃ lsft ┃   z  ┃   x  ┃   c  ┃   v  ┃   b  ┃   n  ┃   m  ┃   ,  ┃   .  ┃   /  ┃ rsft ┃
     lsft   @z_bs  @x_[   @c_{   @v_lp  @b_-   @n_=   @m_rp  @,_}   @._]   @/_`   rsft
;; ┣━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━┻━━━━━━┻━━━━━━┻━━━━━━┻━━━━━━┻━━━━━━╋━━━━━━╋━━━━━━╋━━━━━━┫
;; ┃ lctl ┃ lmet ┃ lalt ┃                  spc                    ┃ ralt ┃ rmet ┃ rctl ┃
     lmet   lmet   lalt                    @nav                     ralt   rmet   rmet
;; ┗━━━━━━┻━━━━━━┻━━━━━━┻━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┻━━━━━━┻━━━━━━┻━━━━━━┛
)

Notice how I explicitly call out things like lsft. What i saw was that the modifier was ignored unless I hold it down for some time (like it had a tap-hold on it) and i would get a lot of missed shifting.

If i change those to _ it improves the situation greatly (though not sure it entirely fixes it. I still get some unshifted behavior, but improved by like 90%)

[dalewking]

Playing with debug log looks like the cases after switching to _ are when I release the shift before the letter. Sp this sequence:

• press shift
• press letter
• release shift
• release letter