I'm having the same problem with my photo. I resized it in Photoshop to be 300 x 300 pixels and is only 44.8 kb in size. It shows the image in my profile as the currently uploaded, but does not show up on any posts I make. Any suggestions?
Once you have uploaded it, position cursor under the signature where you want it to show up, then go back and click on "insert signature picture" on the upper right of the picture, then save.
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2014 Cedar Creek 34 RLSA-7
2015 Chevy Silverado 3500HD LTZ SRW