It is not uncommon for the rear to drop 1.5-2" when using a properly-adjusted WDH.
A drop of 1.25" is not a large amount.
As others have stated -- if you get the front height correct for your TV, the rear end will take care of itself.
If you check your owners manual, I believe it will say that the WDH should be adjusted to eliminate about 50% of the front-end rise.
IOW, if the tongue weight without WD applied causes the front to rise 1", you should adjust the WDH to lower the front end rise to about 0.5"
You definitely should not try to force the front end below the unhitched height.
The WDH manufacturers who recommend doing so are following an outdated WDH-adjustment approach.
Ron