Active fermentation, no krausen

I've got something going on in a lager fermentation I've never seen before. While I'm RDWHAHB about it I'm curious about what might be going on

Here's the background.

I'm making 5 gal of my house dunkel. I've made the beer many times. The only change is 10 of the 11.5 lbs of the Munich is the new Weyermann Barke Munich. BIAB 60 min step mash at 145 - 156 f. 3rd generation WY 2308, my house lager strain. Pitched at 50 f and raised to 52 f. I've got excellent temp control. Standard pitch rate. Fermentation began ~ 18 hours after pitch, about what is expect.

This is now day 3. It is very actively fermenting, but no krausen at all. Lots of small bubbles break the surface and burst, like a soft drink in a cup. SG is dropping as I'd expect. samples don't seem off in any way.

Anyone have thoughts about this behavior? The only difference I can think of in this batch is the Barke malt. Could a different malt protein structure maybe account for those?

I'm not familiar with that grain so I can't really comment on that. Other than adding something with oils (chilis, chocolate, etc) the only other thing that comes to mind is cleaning product residue (PBW, detergent, other) on the inside of the fermenter. Or maybe a previous brew with oily additions left behind.

Had thought of cleaner residual. I'm pretty sure I rinsed before sanitizing with stansan. I guess I'll know when I sample it.