Hello,
I have a big problem since I converted 1.10.2 map to 1.12.2 (and upgrade my server to 1.12.2) : All leaves on my custom map are decaying after I walk near the forest ! :’(
Noooooooo !
Do you know how to fix it ? ! 
Here is no fire, no mob. Leaves are just… decaying even if there is wood blook.
If you’re using Grief Prevention, you should be able to set a flag which stops them from decaying, but that would also stop all leaves from decaying.
Thx for tips, but I want to use basic mechanics, like before with 1.10.2. No plugin or mod to fix that.
Other idea ? 
What mods/plugins are you using? Also include your Sponge version.
And I used Conquest Reforged convertor to convert map to 1.12.2
I asked on Conquest forum too, but no response 