LinkedIn appears to have an inconsistent approach to image posting when it comes to Profiles.
Unfortunately we don't have control over this however, to ensure images are posted correctly we recommend using the following image sizes:
1200 x 1600 Maximum - (Please use this image an as template)
552 x 552 Minimum - (Please use this image an as template)
Still having issues?
We'll take over from here, please submit a support ticket and provide screenshots of the issue and the steps you have taken to replicate it, this will help us troubleshoot the issue further for you.