It seems create dynamic material instance doesn't work in construction script

[Anonymous_17ea3dc4b8ac7adf23f1c0dec82183cc (魔法少女帕斯酱)]

i create a dynamic material instance in construction script, then i set a scalar parameter in event trick.But it doesn’t work.However, i use event Beginplay to create dynamic material instance, it works!! I wonder why i cant create dynamic material instance in construction script.