No huge worries, I think it took 5 or 6 days for me and then the doctor had me take some miralax and then I had the opposite problem for 3 days, then it switched back to nothing for a few days, then the other, and then once I started more regular food things seemed to balance out just fine. Everybody reacts a bit different, but its not uncommon to go a few days. It takes a long time to condense protein drinks down into something solid and stimulating enough for your bowels to let it go, and generally we are a bit dehydrated, so that makes thinks a little harder.
If you get concerned, just call your bariatric team and they'll provide some good guidance if you need to add a laxative or something.