I have to agree with "ThinkTank and "rmtt".
I've been using Musclefeast Isolate and Hydrolysate since 2010, and Never have any Issues.
I only get the Unsweetened/Unflavored, so I'm Not Locked into any one flavor.............. JP
P.S.
I'm wondering if OP's Isolate, is 100% Pure Isolate.
As I've not run into anyone who has Digestive Issues with Isolate or Hydrolysate.
Seems to be confined to Concentrate and the Lactose in it.