Hi,
After writing some journals for the Week of Awesome I noticed a few bugs with posting Journals. When previewing the post all the tags are removed and the selected categories are reset as well. An easy way to circumvent this is by simply saving a draft instead of previewing it, so a short term solution might be to just disable the preview button if it's not easily fixable.
Also, I'm not sure about this, attachments and entry images might be removed as well.