I think LMB are harder to catch than brown trout while ice fishing. I have caught a few but for me they are few and far between hooks ups. Knowing this I don't think LMB are active and aggressive under the ice, but they do eat and can be caught as shown in these recent posts by Dwight from MN and Brad from Colorado. Brad's post shows he caught several LMB on his day on the ice.
See Jan 19 2021 posthttps://forums.pondboss.com/ubbthreads.php?ubb=showflat&Main=40759&Number=529420#Post529420https://forums.pondboss.com/ubbthreads.php?ubb=showflat&Main=40793&Number=529981#Post529981
If you want more active catches of trout ice fishing you should be adding around 100-120 rainbows this year. But get them large enough that your darn bass don't eat them, probably 8"-10" and feed them well so they grow fast ,,,,well beyond prey size for the LMB.