If an image is uploading smaller than what your site/personal page allows you can attempt to reset the page to default then try again.  This should remove any pre-existing limitations and attempt to upload at the size limit that is set.
  1. Select Manage on the TeamRaiser that is producing the issue.
  2. Search for the Team or Participant with an issue.
  3. Select edit on the Personal or Team page.
  4. Make sure to copy the description or anything that has been modified on the customized page and save it in a word document.
  5. Select Replace with Default.
  6. Once the page is default again add back the content that was removed and re-upload the image.
This should now work as expected.