Minecraft Version: 1.16.5
forge: 36.0.42
ExtremeReactors-1.16.4-2.0.22
ZeroCore2-1.16.4-2.0.20

Same problem in #33

1. All the down buttons in the up and down buttons are having clicking problems
   When clicking on the border of the down button, the click can hear the sound, but no response
   

2. Outlet Mode / Eject Fuel / Eject Waste buttons in Solid Access Port GUI are having clicking problems
   

I've checked almost all the buttons and there Shouldn't have the same problem anymore.

I don’t want to take the screenshot three times, so I marked it with a red box, which caused some misunderstandings. It’s not the black border. You can try it yourself to easily reproduce the problem

Ah OK. It's probably the same problem as before, the parent panel being a couple pixel too short. Checking it

Yup, 4 pixel short. Fixed it

For the Access Port, the black border is not part of the button. It's just a decoration.

I'll check the up-down controls

I've increased a bit the up-down hit boxes. It will be included in the next release

Fixed in ZC 2.0.21 & ER 2.0.23