Microsoft Teams Webhook : TEST alerts has images on Teams, but real alerts, not

I’m using a self-hosted grafana version v6.6.2 (3fa63cfc34)

i configured a Microsoft Teams webhook

using the test button,

it send a test alert with image, that is OK

image

using the email alert,

it send alert with images, that is OK

but the alert sent to the same teams webhook mentioned before,

doesn’t has images attached.

what can be wrong?

any help appreciated.

thanks a lot.