I would but I’m temporarily not doing mash, because I’m getting a knee replacement next week, and I’m trying to simplify things a bit for my husband.I suggest you dig a bit deeper than the labels to find out what does or may have gone into the pellet first.
Clearly they are getting what they think they need by ranging, and do not currently want what's in the 'whole grain mash' you're offering too. Can you post a photo of that mash?
The mash was initially made from 18% chick feed and then part chick feed, part layer. Even though the feeds were from the same company (Kalmbach), they were very different in terms of appearance. The chick feed has almost all whole grain plus the fines (no pellets) containing supplements. The layer version has noticeably fewer whole grains and the rest Mystery Pellets. So I can understand the refusal in the chicken attitude of “OMG, what’s that; she’s trying to kill us.”
So I went back to only the chick feed in the mash, but they still noped.
At this time, the weather also began heating up, so maybe that affected the flavor.

At any rate, I’ve decided against the layer feed in favor of chick or all-flock, so Im just feeding it dry and not worrying about waste for now. Ideally, I’d like a combo of non-layer mash in the mornings and dry on hand for when they feel they need it. They’re definitely thriving on the foraging, generally three hours in the mornings and three-four in the late afternoons/evenings.