Just had the same problem. Changed all my .png files to 8-bit 256 color and reloaded them to the /pix/... folders. Worked like a charm. Had read where the TCPDF program (?) gets cranky with anything other than 8-bit .png. Hope this helps.
Cheers
Custom certificate (plugin)
error in 2.3.2
This discussion has been locked so you can no longer reply to it.