FTP Auto Calculation - Trainer not supported?

Can you also power the trainer as a power meter?

No. Have to connect over Bluetooth to get speed and cadence.  It does not emulate those fields on ant+

The kickr should support everything over ANT+. If you’re using a separate cadence sensor is it Bluetooth only? There has been a firmware update for some Wahoo trainers to add native cadence support so worth a look to see if there are any updates for yours. My older kickr (non-core) is supposed to be getting an update early this year. 

Edit: The core definitely supports ANT+ speed and power in the earlier firmware, from 1.011 (Sept 2019) it also supports cadence.

https://support.wahoofitness.com/hc/en-us/articles/360000217839-KICKR-CORE-Firmware-Updates

Cadence and speed are only reported through Bluetooth and yes it is fully updated. Their documentation is confusing, but it only applies to the btle connections. 

Either way it is still reported as it being a trainer, not a power meter. The 830 is looking for a power meter specifically, even though a trainer reports power.  So we end right back where we started, ant or btle. This is something that garmin should account for.  

Can you not use ANT+ to pair as a power meter and BT to pair as a cadence sensor at the same time?

Other option is to buy a cadence sensor and stick it on your bike for cadence and pair the trainer as a power meter via ANT+.

It's not really Garmin's fault if other companies don't follow standard protocols though.

All very strange but according to GPLama you need to pair using FE-C (as a trainer) in order to get cadence, not sure about speed. More on his video here https://www.youtube.com/watch?v=CmXfDvuNyyM

Edit: some more detail from DCR, extract below:

Now note there are some restrictions as of today:

A) It’s *only* transmitting cadence via Bluetooth Smart FTMS
B) It does *not* transmit cadence via normal ANT+ power meter profiles
C) It does *not* transmit cadence via normal Bluetooth Smart power meter profiles

I asked Wahoo why not, and honestly, they quickly agreed it was kinda silly not to send over those profiles. It sounds like they’ll update that in a firmware update. There are plenty of people that pair their KICKR’s to devices or apps that don’t support ANT+ FE-C Bluetooth Smart FTMS trainer control profiles.

https://www.dcrainmaker.com/2019/09/wahoo-adds-cadence-support-multichannel-bluetooth-to-kickr-core-trainers-via-firmware-update.html

Its a trainer, not listed as a power meter.  The 830 specifically requires the power meter profile to do auto FTP detection and the system broadcasts out as a trainer.  I know what you are trying to say, but it is *not* the correct behavior.  The 830 should be able to interpret power from any source.

Yes, this.  I do have a separate cadence sensor as well, but it is a combo speed and cadence.  If I enable that, it loses the speed reported by the trainer.  Which is a big issue.

At the end of the day it doesn't really matter.  The device 830 needs an update to support power from any source as part of the Auto FTP.

OK makes sense, the only thing that confuses me slightly is that you don't get all three metrics when paired as a trainer over ANT+ as the GPLama post implied that should work. The only reason I mention it is that there seems to me to be a slightly greater likelihood of auto FTP working over ANT+ FEC than BT FTMS, although you seem fairly certain it's the sensor profile rather than the protocol, did Garmin confirm that?

I'd try it on my kickr if it wasn't for the fact I'd have to do an ftp test, and this time of year thats a scary prospect ;-)