Audio Render is really quiet

If this has been covered elsewhere, I haven't seen it yet, so feel free to offer a link rather than an answer.

I'm mixing a feature project in 5.1. I've got all my tracks going to respective submixes (Dialog Tracks going to a submix, effect to another, music to another, etc), with said submixes bussing to the stereo Main and the 5.1 mix.

In my home studio (iMac 2019 40gb RAM saffire pro 40 usb audio interface, L, R, C, LFE, LS, RS calibrated studio monitors) the timeline audio sounds stellar. Lush atmosphere, booming music, crisp dialogue, detailed effects, good separation, floor rumbling lows out of the subwoofer, all the automated pans moving sounds around the field as expected. Good to go.

Then I render out my surround stems, and...(cue wah-wah-wah trumpet note)...it sounds terrible. Everything is whispers. Maybe 30% volume at best. The back surrounds are barely audible. The LFE channel has full spectrum sound instead of just the low rumble. I did a render of the stereo main, and same thing. Center channel is decent, but what was L and R heavy is significantly quieter.

I'm new to this, so I likely missed something obvious along the way. Or maybe it's the render settings I'm choosing?

There are a lot of moving parts, obviously, and I don't want to write a novel here, so totally open to the random: "Are you sure you have this specific 'thing' selected, or routed, etc" suggestions. I'm used to the renders I get out of Logic Pro X--where what I hear when I'm working translates directly to the output I bounce.

Any help appreciated! Thanks in advance.

What format are you rendering to?

As far as the LFE, are you using and kind of filter on the LFE bus in your mix?

Are you sure the channel format on the output is correct? If your LFE is playing full bandwidth content that might mean it's getting the wrong track from the output file.

Resolve doesn't have the best export options for audio outside of WAV format, and even that has some drawbacks.