[eluser]goFrendiAsgard[/eluser]
Confirmed, In my case, the configuration value is @base_urlassets/nocms/images/custom_logo/0_61_nebula_ngc2818_hubble72 (without extension)
But the image still appeared correctly. I still wonder what is the cause of this symptoms. I think it is related to qquploader library which I use as ajax upload library.