Troubleshooting tips:

1. Modpack isn't loading / launcher error: I always recommend using Gale Mod Manager or r2modman over the Thunderstore app, as this solves a good majority of these problems.
2. Can’t connect to friends: This commonly occurs when one person presses the “update all” button and one person doesn’t; everybody has to be on the same page if they’re going to update all.
3. Other: While pressing “update all” usually doesn’t matter, sometimes updates need to be adjusted to avoid incompatibilities, so usually it’s best practice to leave the updating to the pack owner.

If none of this works though, feel free to contact me. I tend to respond fairly quickly.