I’ve done this aa few times and it could just be my digestion reaction. I have Huel in the morning, and I’ll sometimes have Ambronite for lunch (doesn’t matter the EU flavor). The combination = CH4 (methane). The problem many have when starting out on Huel, etc. Gas. I’ve been taking Huel for a long time and no worries. But if I follow with Ambronite… catastrophic results 
Wow. I’ve done it a few times to see if it was a fluke. Nope. Just a warning. I far prefer Huel, I just have a box of Ambronite sitting around that I feel guilty about if I don’t use.