Only audio is uploading without its video

I would be happy to try and help.  But, you need to offer more than "Seems to want to play video but mostly not.".   

I've used Premiere Elements since version 9 on ordinary laptop computers.  I know it works and works well.  Something is wrong somewhere in you settings, your footage, your preferences or even your hardware.   It may take some patience.

Newer phones can use the HEVC/H.265 codec.  In the menus for phones will be choices like "most compatable" or even not selecting HEVC.   That will make most phones record in the more universal H.264 codec.   The difference is not in image quality as much as it is with file size.   The H.264/MP4 combination should work well with older versions of Premiere Elements.

Try using https://handbrake.fr/ open source transcoder/converter to convert to a different codec

From your description it seems pretty clear that in the 7 years or so since PE12 was developed & released that phones progressed and your new phone (type unspecified but is presumably more recent than 7 years) uses a video encoding that was not existing back in those days.

The fact that you showed that PE2021 can handle your phone video shows that Adobe has added new capabilities since then.