Just upgraded to discourse 2.2.0.beta8 and it seems to throw up this warning:
When I click on the link, I see that I have already uploaded an image for the same. I did try re-uploading it, but it still gives the warning. What am I doing wrong?
(The Splash logo size is 2434px x 2437px)
The image must be a 512x512 PNG as said in the setting description.
I suggest to change the wording to make clear it’s a requirement and not a recommendation. Same applies to short_title.
I would agree, as I had this same issue and it says Recommended not Required.
Thanks for the recommendation, we’ve updated the texts in multiple places to hopefully make this better 
https://github.com/discourse/discourse/commit/67a7670bab8ce1793b7e7db11109038afcd834e8
https://github.com/discourse/discourse/commit/1a39f6fd5d14f1942b700e9648eb4cbafff4a682
https://github.com/discourse/discourse/commit/88546bfe005fb64545dc2b08b0e00be5b15296ee
