HEB systems appear to be down across all stores for an unknown reason.
At 12:32pm CST we received a text from the company’s automated service: “We are experiencing technical difficulties across all locations. Orders may be delayed.”

Then at 2:03pm another message: “We are experiencing ongoing technical difficulties across all locations. Orders may be delayed.”

A thread on reddit.com/r/austin describes that customers are unable to pick up curbside orders and in-store registers are unable to process orders unless paid with cash. Additional reports suggest some stores are semi-operational.
UPDATE 2:32pm — A source at the Riverside location has confirmed their systems are back online for processing orders and pickups. Curbside orders will be slightly delayed, but it seems they’re pulling off a relatively quick recovery from the system-wide issue.