Homerow Mods make dead key working intermittently

[lou-bi]

On my Corne 42, for french accents, I've notice that when using dead key, it works intermittently.
Xudongz on Discord did help me tracking the issue, and it works well when using the &kp APOS + &kp x code, but sometimes works, sometimes not with &kp APOS + &hmr x x.
Is there some kind of setting to adjust to be able to use both your timeless HRM and the dead key ?
I can give more details if needed, but I don't think the debug process was relevant