I succeeded to transform a heat block in a warm core in the begginning of my game but now if i tried to ignite a Heat block he blows up and sometimes makes diseappear near block visually, if i put another block in the missing block, it updates it. But the Heat block is always a heat block.

this problem have a solution ? i tried to reload my game. maybe dowload again the mod pack and put my save in will be a solution ?

Check to see if you have claimed the chunks.
I was having the same issue and checked the requirements on the wiki, the block needs to be destroyed by an explosion (which it triggers itself) and claimed chunks prevent explosions from breaking blocks.