Quick answer: Verify events in the GA4 DebugView in real time, register custom parameters as dimensions, and wait out the processing delay before judging standard reports.
Your custom level_complete event with a level_id parameter seems missing because the parameter was never registered and standard reports lag a day. DebugView and parameter registration resolve it.
How to fix it
1. Confirm in DebugView
Enable debug mode and watch events arrive in GA4 DebugView in real time to prove they are being sent. If they appear there, the issue is reporting, not delivery.
2. Register custom parameters
Create matching custom dimensions in GA4 admin for any event parameters you want in reports. Unregistered parameters are collected but not queryable in standard reports.
3. Wait out processing
Standard GA4 reports finalize after 24-48 hours, so do not conclude events are missing from a same-day check. Use Realtime and DebugView for immediate verification.
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 HTML5 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.
A crash you can name from its stack trace is a crash you can usually fix in minutes.