if_tap hold question

[urnati]

Hi-
My end goal is a single key that, on tap, double tap, hold produces key, Alt+key, Shift+key respectively.
When attempting hold, I ran into an 'issue' that hold worked on one device but not another.
Double tap works fine on both devices (from the site example of nested if_tap).

My basic question is - where or what do I need to look at to resolve this?
Below is some data I have collected. Any pointers would be appreciated. And I would be happy to provide additional data.

-- Code used : This is a simple test on a single key on each device; default settings on each; both devices are USB direct into a desktop (no hub)
-- Output to a simple text editor
if_tap(key(a), key(b))

====== Does NOT work : Get 'a' on single tap; no 'b' on hold or release of key
$ sudo evtest /dev/input/event4
Input driver version is 1.0.1
Input device ID: bus 0x3 vendor 0x16d0 product 0x113c version 0x111
Input device name: "Azeron LTD Azeron Keypad Keyboard"
...
Event: time 1737644873.445274, type 4 (EV_MSC), code 4 (MSC_SCAN), value 7003b
Event: time 1737644873.445274, type 1 (EV_KEY), code 60 (KEY_F2), value 1
Event: time 1737644873.445274, -------------- SYN_REPORT ------------
Event: time 1737644873.700470, type 1 (EV_KEY), code 60 (KEY_F2), value 2 <= repeats

====== Works : Get 'a' on single tap; get 'b' on hold after default timeout
$ sudo evtest /dev/input/event7
Input driver version is 1.0.1
Input device ID: bus 0x3 vendor 0x46d product 0xc24d version 0x111
Input device name: "Logitech Logitech G710 Keyboard"
...
Event: time 1737645089.504017, type 4 (EV_MSC), code 4 (MSC_SCAN), value 7001f
Event: time 1737645089.504017, type 1 (EV_KEY), code 3 (KEY_2), value 1
Event: time 1737645089.504017, -------------- SYN_REPORT ------------
Event: time 1737645089.756490, type 1 (EV_KEY), code 3 (KEY_2), value 2 <= repeats

[urnati]

Answered, user error :)