Grinding sound after a new chain, but only when using the chainring I hardly ever use

I’ve been running a full SRAM Red setup since August 2022, with a 48/35 chainring and 10-33 cassette. I’ve used Silca Synergetic lube the entire time and have kept the chain very clean. The setup has ~2,000 miles on the road and ~2,500 miles on a Kickr (with a Force 10-33 cassette). While on the road I mostly use the 48T chainring, with the 35T basically only being used when climbing steep hills in the two largest gears in the back. On the trainer I only use the 48T chainring.

A couple weeks ago I broke the chain during a sprint. Other than breaking… the chain looked to be in good condition, and didn’t show signs of needing replacement. I even had a shop near me take a look and they measured the chain to be within stretching tolerance. They were very surprised to hear how many miles were on the chain.

Now that a new chain is installed I’m getting a loud grinding sound when using the 35T chainring under heavy load. On a stand there’s no perceivable sound and it doesn’t look like the derailleur is coming into contact, etc. Everything sounds perfect on the 48T.

The first thought is I went way too many miles on the previous chain and the chainring or cassette are now too worn, however they both look fine from a visual perspective and I’ve spent probably 90% of my riding in the 48T chainring so it doesn’t seem to make sense that it is quiet but the 35T is grinding/damaged/etc.

Thoughts on anything I should check? It seems like an expensive game to start replacing the front chainring or cassette.

Did you try trimming (in app or by hitting the shifter together with the axs button on the shifter)?

I just tried trimming the rear derailleur in the app but it didn’t seem to make a difference. When I trimmed it too far in either direction it would jump to the next gear, but then go back to normal when I trimmed it back toward the middle settings. The grinding when in the 35T chainring was consistent the whole time. The regular drivetrain noise just got louder as I went away from the previous setting (setting 7 in the AXS app).