Answer a few questions to find out where your tracking parameters are being dropped.
Is the redirect managed by IndexPlane?
Check IndexPlane → Redirects and search for the source URL.
Is the rule’s query mode set to “Ignore” or “Exact”?
Open the rule and look at Query parameters.
Switch the query mode
“Ignore” and “Exact” can drop extra parameters. Set Query parameters to Pass and save, then run the redirect tester. See Choose a query matching mode.
Does the redirect tester show the parameters surviving?
Paste your URL with ?utm_source=test&gclid=test into IndexPlane → Redirects → Tester.
The redirect is fine; something after it drops them
The final page, a second redirect on your server or CDN, or a booking engine may be stripping parameters. See Keep _gl and UTM on booking-engine links.
Another plugin or the server handles this redirect
Edit the rule where it lives, or move it into IndexPlane so the tracking-parameter guarantee applies. See Redirect conflicts with other plugins.
Contact support
This looks like a bug. Copy the diagnostic block from IndexPlane → Diagnostics and ask in the forum, or contact support if you have Pro.