Minecraft: 1.12.2
Forge: 14.23.5.2847

Mods: 2
cyberware-1.12.2-0.2.11.21
jei_1.12.2-4.15.0.291

NOTE:
This may take a couple tries to pull off.

With at least one Wired Reflexes installed it increases your attack speed... however if you toggle it on/off it sometimes won't apply it's speed boost although it depends.

I'm holding a Diamond Axe since it has a slow attack speed and I install the Wired Reflexes, I see that the speed increase is there since I can attack faster with the axe. Now let's toggle the Wired Reflexes off & on.

While holdin the axe... attack and then toggle the Wired Reflexes OFF, swap to a empty hand and punch the air then toggle the Wired Reflexes ON, then switch back to the Diamond Axe, if by any chance the bug occurs... the speed boost won't apply even though the Wired Reflexes is ON. This will take a few attempts for the bug to occur but when it occurs... one safe way to get the speed boost back would be to reinstall the Wired Reflexes, to 'reset' it.

I have enough power as I have that Cardiovascular Coupler installed which gives +6 power and the power drain is -5 since I have the Myomer Muscle Replacement & 1x Wired Reflexes installed.

If you want me to get a video of the bug just let me know. It MAY be due to toggling the Wired Reflexes off & on after attacking but not 100% sure on that.

Is it reproduced in single player?
Is it reproduced in multi player?

I've only reproduced it in Single-Player. Unsure about Multi-Player.

Tried that already, although if I fight with it enough times by randomly attacking after turning it off/on it will fix itself.

EDIT
Tried waiting at about 10+ seconds and turned it on, that seems to fix it as well.

Try keeping Wired reflexes disabled for a few seconds, then re-enabling it, see if that fixes it.

Fixed in dev