Can't use custom map icons on custom maps in web legend

sample data is italicized

Hi on the dynmap I have 3 maps in the world named flat, surfaceday and surfacenight in the images folder I named the icon file: "block_world_surfaceday.png" last time it worked on 1.14 when i tried to use dynmap, but this time nothing was displayed only black icon, it was supposed to be fixed in the latest dynmap beta version I use now but the only thing it caused it's just that no matter what I do, I'll name the icon file so one and the same flat map icon is applied to all maps in the legend. When I try to set it manually with the command, there is again a black icon. I don't know if it's just a dynmap error or I'm doing something wrong but please help .. thank you in advance. It tried to look at web elements with CTRL+SHIFT+I and find out that every map has style="background-image: url("images/block_world_flat.png");" as image and cannot be changed with command in game

• Dynmap Version: v3.1-beta-4
• Server Version: Latest paper spigot build-240 uploaded: 17. 10. 2020 20:55
• Pastebin of Configuration.txt: https://pastebin.com/vftPfTXR
• Other Relevant Data/Screenshots: *https://i.imgur.com/6YM7WK7.png - web elements, https://i.imgur.com/Yz8A92a.png - before "fix", https://i.imgur.com/WMHipTM.png - after fix *
• Steps to Replicate: Just create custom map with custom name and give it custom png icon in 16x16 and you will see

[ ] I have looked at all other issues and this is not a duplicate
[ ] I have been able to replicate this on my Windows computer

I tried to solve this issue on Reddit but no answer whole month so im trying here now..
https://www.reddit.com/r/Dynmap/comments/iitjgj/cant_use_custom_icons_on_custom_map_in_legend/

closing due to age