Firepower PAT Pool. Keep Same pub IP with Round Robin?

We have a PAT Pool that has been set up in FP for years without issue. Suddenly, there is a single web site that keeps killing users connections because 'their IPs are changing mid session'. They do send a pic showing that the user is logged in with an IP from the PAT pool & then just a couple minutes later, they have a different IP from the pool.

Is the best option to help ensure the same internal IP keeps the same external IP from the pool for their whole session to check the 'Use Round Robin Allocation' box? I think this because of this snippet from this Cisco doc, though I haven't seen it anywhere else.