Slack only updates on some managed devices

We're using Hexnode MDM for our Macs, and have about 150 devices in the company. When Slack updates, only some of the devices get the new version. Hexnode says the VPP token is being pushed to the devices, so it's some VPP problem. We have more than enough licenses, and every device is connected properly. Does anyone have any idea why the same app on the same OS with devices in the same MDM doesn't update for all devices?

There's no correlation between which devices don't update. Most are on the latest version of Sequoia, a few are still on the latest version of Sonoma, they all have the same MDM profile, are on the same network, etc.