Lewisville pattern change?

I know it's crowded with lots of fishing pressure but in late May, June, and early July I can catch sand bass but the last two outings (last night and tonight) I fished from north to south and everything in between. I think something has changed. I saw no sandbass on the bottom. I think they are all mid-water column under the shad but not busting the top. I could not catch these with a hell pet combo or a slab. I have had a fishing calendar for the last several years and I have a big hole for the mid of July through about early August. Frustrating two days of taking out friends and almost nothing was caught. I'm obviously fishing an out-of-date presentation for a pattern that isn't happening. Any advice on my method would be appreciated.

time to troll

Thermocline is setting in. Fish will not be below it

When I fish with slab and jig combo I chunk a reel back when fish are not as active

The thermocline came and went at the beginning of July for most of the Lake. IF you arent fishing with live bait then it has been a struggle except for a few place that we are still catching them on Slabs. Its just that time of year where they arent schooled us as much and they are constantly on the move.

Go out and pretend you are largemouth fishing. I went out on Lewisville Thursday to do a little bass fishing. Launched at Tower Bay ramp at 7am and there was a big school of sandies busting shad just outside the tires. Went across the lake to the cut going into the Pier 121 marina and again, large school of sandies busting shad by the no wake buoys. Went into a main creek going north up the lake (just south of the Little Elm bridge/boat ramp) and just about every point (secondary points-not the main lake points) had schools of white bass on them. That action lasted until about 11am as far as I can tell. Mind you, these might have been smaller sandies but i did see some nicer boils in the mix. I could see the shad jumping out of the water and they were all less than an inch long. I'm guessing if you went point hopping and kept moving with a smaller slab (or inline spinner) you could catch a few. Bigger fish may be below these roving schools.