40km ER4 QSFP+ are they hard to get working or is it just me?

I am trying to test out some FS.com QSFP+ 40g ER4 40km in some Juniper ACX5k boxes. Out of 4 modules I can't get any to work with just a patch cable back-to-back. However this is my first rodeo with 40gig 40km; I have some other 10km "regular LR4" that seem to work fine among themselves.

So among the 4 ER4's I have to test, I see these behaviors:
A-DDM reports no RX light on any lane of 4
B-DDM reports RX light on 2 lanes of 4
C-DDM reports TX light of -5 to -6dBm when for a 40km module the tx should be 0 to +2 or so

"B" connected to "C" magically started flapping up/down after sitting idle for a few days despite the weird rx light readings, and then a few days later started staying "up". I trust that as far as I can throw it. Changing patch cables changes nothing.

Swapping QFP+ between slots, the behaviors track the QSFP module so I don't believe I have any bad slots. At first I worried that I was destroying the receivers but the rx damage threshold for ER4 I believe should be less than the max tx power, yes?

I'll try some other JUNOS versions too maybe, this is all in ACX5k with 17.4R2. I'm running out of ideas before I go crying back to FS.com that they sent me 4 bum modules of the most expensive variety I've ever bought. I've never seen this many issues before with 10g SFP+ or 1g BIDI or ... the cheap stuff...