Index Sleep Monitor no body battery data - workaround doesn’t solve the problem.

Same situation here. Garmin-Tracy Can we get an update on whether there are plans to address this in a future update beyond what's been done in 2.70? If not, I will need to return the ISM, as there's no benefit for me over a watch if it doesn't record body battery info. 

What watch so you have? Most likely you are not on the list of compatible devices. Check my thread here:

forums.garmin.com/.../still-no-body-battery-with-fenix-6x

Thanks. I have a Tactix Delta, definitely not on the list… Garmin-Tracy Is this correct? Will the Index Sleep Monitor not work with my Tactix Delta?

Garmin-Tracy, can we get some clarity on this? There is conflicting information on the body battery trueup site and the individual product specifications. For example, the Fenix 6 is not on the body battery true-up site (Body Battery Frequently Asked Questions | Garmin Customer Support), but on the Fenix 6 product page (Garmin fēnix® 6 | Multisport Fitness Watch), trueup is an included feature for the watch. I have a Fenix 6 and am running into this same issue.

I assume that True Up in the specs refers to "Physio True Up" which does not include "Body Battery True Up" that came a few years after. 

Yes it's confusing :( 

If that's the case, that is incredibly misleading given that there are 2 separate lines on the spec sheet for "Trueup" and "Physio Trueup". 

yes, really confusing and misleading. I'll send my sleep monitor back.

Replying to my self  True Up is defined here : https://support.garmin.com/en-US/?faq=a2uguZzTQG4I2HTBvHa0gA and is different than Physio True Up.

BB is in the "True Up" definition - but only for compatible devices.

Still it's a mess and I would be equally frustrated in your case.

Update as of 8/28/25

Hello Everyone!

After researching further we now know

1) As @jneuveglise surmised, the Index Sleep Monitor must currently be paired to device that is Body Battery TrueUp capable for the Body Battery information to be recorded in Garmin Connect. The list of devices meeting this criteria can be found at Which Watch Models Keep Body Battery Data in Sync

2) We are actively reviewing options to improve this behavior moving forward and hope to have a better process in an upcoming software release(s). That being said, there is not a timeline for those updates and the assumption is that they will not occur in the next 30 days (My attempt at transparency for those who have mentioned they may return the device)

3) For devices not on the above mentioned list, A workaround was posted in the following post. it MAY help some folks.

forums.garmin.com/.../1965083

Garmin-Tracy Body battery data from the ISM is missing in the Garmin Connect App. 
My watch is an Instinct Solar, which I believe is not compatible with TrueUp. But I only review my health data in the Connect app, not on the watch, so I don't care whether ISM data syncs to the smartwatch. I would be satisfied to have ISM body battery data in the Connect app, but I don't. 

The nights when I slept with the ISM alone are August 1, 2, and 3. No body battery data was recorded for any of those nights, even though the ISM recorded advanced sleep tracking, stress, and HRV. 

I am currently running a half-hour test of the ISM again, following the workaround in the OP, to create a new record of what happens when I follow that workaround on the latest firmware.

You may use my data for troubleshooting, and please add me to the support ticket.