So I am recording videos using my DSLR Nikon D3500 Camera which records them in .MOV format.

When I converted them to MP4 using dBpoweramp Video Converter, they played just fine on my computer but when I copied them to my phone and then uploaded them to Instagram, they didn't show the first part of the video as a thumbnail as usual but instead they were showing a black/blank screen.

I tried a few videos to ensure it wasn't just that one video and they all have the black thumbnail.

Then I tried to convert those same videos using Nero Recode 2019 and they appear just fine with the thumbnail when uploaded to Instagram.

Can someone from support look into this please?