Index Issue Outside vs. Trainer

I have a bit of an issue that I’m trying to figure out with my trainer setup.

I have a kickr snap that I use with ERG mode. I have a Giant Defy that I use as my main road bike/ trainer bike. When on the trainer I have a dedicated wheel/trainer tire that I swap out for indoor use. I use a 11-28t Ultegra cassette on the trainer wheel and a Sram Red cassette on the outdoor wheelset.

Recently, i did a tune up and now the the cable tension for my outside setup has been different than inside. I’ve installed new cables, installed a new chain (I keep it relatively clean and lubed) but it appears the indexing is off. I had to make 3 full turns of the barrel adjuster on the RD just to get it within compliance on the cassette. Each time i ride outside, i have to adjust the cable tension to make it shift well. Then when on the trainer, i have to adjust again. This issue didn’t surface until the recent tuneup. The cassette and chain rings don’t look worn enough to be the cause. What could be causing the issue?

I took the wheel off as I had a spare. Looks like there was play in the freehub /cassette. I thought it was a tension issue with the snap, though doubtful as I haven’t had an issue for the last 1.5 years until recently. I put the spare wheel on and the shifting, or chatter, I was experiencing is now gone.