Server group icons larger than 16x16 will not be displayed.
I just changed my icons a few days ago and also checked what size they are. They are all 512x512 and display perfectly fine. I don´t think I made them smaller by resolution before uploading, I only reduced their file size through tinypng because TS3 told me that they were to large to upload by file size.
I deleted and re-uploaded the icons, but it still doesn’t show me. 
we use 32x32 and its fine 
16x16 is the old resolution
