tx-rate set is largely ignored by anything that is a 11n or higher client - which will more generally use HT and VHT rates for traffic. Unless you have really old clients, those rates are is more often utilised by management & control traffic. Please ensure that if you are raising the tx-rates that the basic rates are raised too to match the lowest one or two configured tx rates.
This old post kind of goes into the various options
https://community.arubanetworks.com/t5/Controller-less-WLANs/Customize-802-11-rates-on-IAP/ta-p/273299
but, in 802.11ac it's not possible to slice out the low VHT rates (if i recall correctly right now), so attempts to corral the users to a tight range of tx rates are generally futile (and may not serve any purpose, see next point)
To your latter comment about disconnections - best to try and narrow it down before changing things - is it ARM, is it beacons is it RF etc.
What band are the clients on and what kind of radio do they have, would be a starting point. Also, what is the AP density and what is the typical tx power being used by the APs ? What is the current setting of the rates ?
To speak generally about problems that often crop up in warehouses are things like bad/uneven tx power, 2.4ghz interference, frequent channel changes (for various reasons).
We can debate it a bit more in here, or, you might get some benefit to kick off another thread titled more around warehouse problems to see what the community has to say.
-jeff