There are two common reasons that we can't explode blocks on ZWCAD:
a: when creating the block, the "allow exploding" is unchecked
b: the block is xref
Solution:
On ZWCAD 2018, double click to execute the block editor, can copy all objects in the block from block editor, then close the block editor, paste the objects into the drawing
If solution above doesn't work, please try to following steps:
1. type the wmfout command.
2. select the block, then save it to anywhere of the PC.
3. type the wmfin command, select the file that just saved.
4. type x command to explode the block