Last few betas had the same issue, since EXR is my main format I just stopped using the Photo betas and forgot about posting about it again.
Some EXRs show up in the navigator (Quixel's do) but aren't rendered in the Canvas. Regular EXRs from Nuke don't render anywhere. ACES compliant EXRs don't render either. This bug is new to the 1.7 betas. The retail version still works fine with EXRs.
Same goes for Jp2. You open a JP2 and both Navigator and Canvas stay blank.
With the exception that Jp2s crash the retail version.
Are you sure this isn't related to OpenColorIO with Metal compute? (I'm going to assume you use OCIO)
The whole OCIO pipeline is currently broken with Metal compute—if you disable Metal compute and switch back to software under the Performance preferences section everything should work fine. I've been opening EXRs produced from various software (with OCIO configured) and haven't had any issues. The developers are aware of this and it should be fixed soon.
If that's not the solution to your issue, it would be great if you could provide samples as Gabe suggested so we can have a look. Thanks!