Engineer's Thumb + Buff n Blend -- Problem (no compression, quiet)

[Mo3hre]

Hi guys,
I've built an engineers thumb (from kit) and am trying to add a Blend knob with buff n blend (also kit). The engineer's thumb works nicely on its own. However, if I add the Buff n Blend and turn the blend knob to all wet, it's only unity gain, but with noise and without noticeable compression. I have the feeling that the input from Buff n Blend to engineer's thumb is too weak and therefore it never crosses threshold to compress. If I run the engineer's thumb on its own, it's much louder and compression is very  obvious. Also, if I turn the 'ratio' knob of engineer's thumb all the way down, there is no signal anymore. Is it supposed to be like that?
I'm quite new to building pedals and I really hope you guys can help. I loved the sound of the engineer's thumb, adding the buff n blend is a little ambitious for me but man would that sound cool!

[GibsonGM]

Link to B n B pdf schematic.    https://guitarpcb.com/wp-content/uploads/2018/06/BD_Buff-N-Blend.pdf

Sorry if this is obvious, but did you determine that the Buff works as it should, using another pedal or dry signal?

[Mo3hre]

Yes, I shorted send to return, which gives dry signal (wet=dry). See picture. I was also worried about phase cancellation, but from what I've read the engineer's thumb doesn't invert phase. The engineer's thumb PCB has two spots for +9V. Usually the top one (in picture) gets soldered to the DC connector, and the bottom right one is connected to the 3PDT switch. I soldered both to the +9V connection on the buff n blend pcb, is that correct?

[blackieNYC]

The 2nd 9v connection goes to the switch for an LED.  No harm in how you've connected it. 
The short that you tested your buff n blend with should be fine, but I would also try with a pedal you know and trust that does not invert phase.  Just 'cuz.  Though yes, the ET does not invert phase/polarity.