What version of Premiere Elements are you using on Windows 7 64 bit?
What were the pixel dimensions of the stills that you brought into the project?
What 4K video - 3840 x 2160 or 4096 x 2160? What is the brand/model/settings of the camera that recorded the video?
What was set as the project preset for this project? See Edit Menu/Project Settings/General and the settings for Editing Mode, Timebase, Frame Size, and Pixel Aspect Ratio (even if the fields look grayed out).
When you talk about rendering, I am assuming that you mean rendering in the export sense of the word and not rendering in the Edit area previewing sense of the word.
In order to determine what is going on with the file size, we need to know full details of the export settings, especially the bitrate settings.
If any problems gathering the information requested, I will offer more detailed suggestions to help you find the troubleshooting information requested.
My first impression is that your issue relates your choice of project settings and export settings.
Please consider. We will decide what needs to be done based on the details in your reply.
Thanks for quick answers:
1) Elements Premiere 14
2)3840*2160 Pixel jpeg file - Camera Nikon D7100,
Imported videos were in mp4 file, camera type should not be relevant should not be relevant, videos and still photos were running o.k. when export was done for HD resolution, problem only with 4K export
3)I have not changed the default settings since installation, settings:
page picture moving(?)
all items ticked
4)Rendering in export sense
5)3840x2160 , format MP4 XAVC-S
Audio AAC, 160kBit/s, 48kHz, stereo
Duration 5Min.53,53sec. -----took much longer for my test project
My test file got stuck, when it showed remaining 98% and Time remaining 0:00:00
I switched over to HD1920X1080, resulted in same duration as 4K, Filesize ONLY 662,90MB at Bitrate of 15MBps