Not yet... just saw this
http://iamatexan.com/2020/03/16/reports-walmart-stops-selling-guns-and-ammunition-in-texas/
Thanks....from your (TX Walmart/ammo) link...
...Verdict: This particular (unverified) Walmart probably didn’t have anybody on shift at the time who was qualified to sell ammunition and placed this sign. It is not a likely conspiracy to keep ammo out of the hands of law abiding gun owners...
(Not seen at any other TX Walmarts, by the website.)