No Prevew Thumbnail

[previewer]

Background Info:
Version: VLC 2.2.4 WeatherWax
Original video file format: MP4/FLV
Converted video file format: MP4

Status:
(A) Original video file: It is able to show preview thumbnail after it is sent/received by WhatsApp.
(B) Converted video file: It is unable to show preview thumbnail after it is sent/received by WhatsApp. Instead, it shows only a grey preview thumbnail

Question: Does some setting (what I miss) enable the converted video file to show "proper" preview thumbnail (as the original video file does) after it is sent/received by WhatsApp?

(Please kindly move this thread to the proper forum if it is posted in the wrong place. Thanks. )

[robUx4]

Not really. It may be WhatsApp that takes time to generate the thumbnail.

[previewer]

Not really. It may be WhatsApp that takes time to generate the thumbnail.

Thanks for your reply.

Sorry for not writing my problem clearer previously.

Actually, the converted video file is unable to show preview thumbnail after it is sent/received successfully and downloaded completely by WhatsApp. Instead, it shows only a grey preview thumbnail.