Did you check “Allow exploding” when defining a block ?
If the blocks are not minserted blocks, check if you have unchecked the “Allow exploding” option when defining your block, as shown in the following picture,
To allow exploding, double-click the block to enter Block Editor, if it’s an attribute block, you can use BEDIT command to enter Block Editor.
Do not select any object, just open the Properties panel using CTRL+1, and find the “Allow exploding” and switch to Yes.
Then close the Block Editor and save your changes to the drawing.