Quick answer: Distinguish loaded state from pending changes in the UI, show which mods need a restart to apply, and apply live where the loader supports hot enable/disable.
Your mod manager shows a mod as enabled, but it is clearly not affecting the game until a restart. The cause is the UI reflecting the config you are editing, not the mods actually loaded this session, with changes only applied at next launch.
How to fix it
1. Separate loaded vs pending
Track two states: the mods actually loaded this session and the pending enabled set the player is editing. Show both so the UI does not imply a change is live when it is not.
2. Flag changes needing restart
Mark mods whose toggle requires a restart and show an Apply/Restart prompt, so the player knows the difference between done and pending.
3. Apply live when possible
If your loader supports hot enable/disable, apply the change immediately and update the loaded state, so simple data mods toggle without a restart.
4. Persist intent, reconcile on launch
Save the pending set, and on next launch load exactly that set, then sync the UI to the resulting loaded state so display and reality match.
Catching the ones you can't reproduce
The hardest version of this to fix is the one you can't reproduce — it only happens on a player's hardware, OS, driver, or save state, under conditions that simply aren't present on your machine. A report that says “it crashed” or “it froze” gives you nothing to act on, so the bug survives release after release while quietly costing you players.
Automatic error capture closes that gap. Each failure arrives with its full stack trace, the device and OS, the build number, and a breadcrumb trail of what the player did right before it broke, so even a failure you have never seen becomes a specific, reproducible issue. Fold identical failures into one signature ranked by how many players each hits, and your worklist sorts itself worst-first instead of arriving as a stream of vague complaints.
This is where a tool like Bugnet earns its place. Its SDK captures every error automatically with the full stack trace plus device, OS, memory, build, and game-state context, folds duplicates into one grouped issue with an occurrence count, and ties each to the build it first appeared on — so you fix the problem that hurts the most players first and confirm it is gone when its signature disappears from the next release.
Reproduce it once with full context and the fix writes itself. The hunt is the expensive part.