When I convert a keynote to PowerPoint to share the pics move around and some disappear. What am I doing wrong ?

Salutations Walkdog21, 

This may have to do with the compatibility, source, etc of the image. After exporting the presentation from Keynote are you then relaunching the PowerPoint version in Keynote or launching it in PowerPoint? Are there any similarities in the sources of the images you’re using? 

Convert Keynote presentations to PDF, Microsoft PowerPoint, and more

If you’re not using the following steps for the export, give them a try - 

Convert a Keynote presentation in Keynote for Mac

If you want to open a Keynote presentation in another app like Microsoft PowerPoint, use Keynote to convert the presentation to the appropriate format.

1. Open the Keynote presentation that you want to convert.

2. Choose File > Export To, then select the format. If the file needs to be compatible with an older version of Microsoft PowerPoint (1997-2003), click Advanced Options, then choose .ppt from the pop-up menu.

3. In the window that appears, you can choose a different format or set up any additional options. For example, you can require a password to open an exported PDF, choose the format for an exported PowerPoint presentation, or adjust the timing of the presentation if you're exporting as a movie file.

4. Click Next. 

5. Enter a name for your file and select a folder to save it to.

6. Click Export.

To send a file in a specific format through Mail, Messages, AirDrop, or Notes, choose Share > Send a Copy, choose how you want to send the presentation, then choose a format.

Thanks.