Video Thumbnails with Front End publishing

Hi,
I use video thumbnails plugin in addition of ACF (Advanced Custom Fields).

Everything is ok when publishing from admin panel of wordpress: user put the video url in an ACF oembed custom field, the video thumbnails plugin generate a video thumbnail when i click publish in wordpress. Cool ??

But i have set a front end publishing form with ACF. User on frontend can create a video post, put a video url (eg: youtube) and publish from frontend. Custom fields are exactly the same as custom fields on backend admin.

Video thumbnails plugin fails to generate the thumbnail imediatly when a post is created on frontend. We have to go on backend wordpress admin, select the post created before on frontend, and then click on publish to allow video thumbnails plugin to generate the video thumbnail. Weird, no ?

I have added the right custom field name in the plugin settings (oembed), why is it not working with this field when a user publish from frontend ?
What i have to add in my code to allow the plugin to capture the oembed field before the frontend post is saved (as it do it when we publish the regular way)?

Thank you for your help and sorry for my english ??

PS: i’m working localhostly

https://www.ads-software.com/plugins/video-thumbnails/