Note: if you need general tech support for things like server configuration, Discord is a better venue. Please open an issue only if there is a clear bug with the pack or if you have been asked to by one of the Discord staff.

Pack Version:
1.2.2 with Fixed Jars installed.

Description:
After you go to the moon for the first time. Normal rain only happens for about one second before stopping.

Expected Behavior:
It rains.

Steps To Reproduce:
Go to the moon.

Crash Log:
If your client crashed as a result of this bug, please upload the generated crash log. This is found in your launcher's Omnifactory profile (aka instance) in a folder called crash-reports. If there was no crash, but instead an error screen, please upload your latest.log instead.

Screenshots:
If applicable, add screenshots to help explain your problem.

Rain is not supposed to occur on the moon, since there's no water or atmosphere to support such a thing.

The downfall starting then stopping is a bit strange; I don't think I've ever seen that. Are you leaving a raining overworld and landing on the moon? If so then it's probably just a quirk of how toggling downfall takes a few seconds.

Why on earth are you expecting rain on the moon?

You are misreading the problem (granted, it's not explained well). I'm experiencing this issue on my server now. Here is a clearer description of the issue:
Step 1: Go to moon
Step 2: Go back to the overworld

Results: Whenever rains in the overworld the rain starts for a fraction of a second and then immediately stops. Even toggling downfall with server commands causes the rain to start for a fraction of a second and then immediately stop. Restarting the server does not help. Installing unnofficial fixes does not help (and the issue was occurring pre-fix installation as well).

I can provide video you if want.