getting error when load uobject or actor that useing other asset in pak file

When loading uobject asset that using other asset(in same pak) from mounted pak file. I got this error while i can still using this uobject to spawn the actor.
and I got the same error when tried to loading actor that used other asset too.

I don’t think i did something wrong when mounting pakfile and there isn’t any error when load asset that dont use other asset.
I didn’t load other asset before loading this uobject. or I should do? I think when adding any asset to BP, UE4 will automaticaly load that asset for you.
and I dont think loading asset manually is a good idea too.

There isn’t crash or bug. but when it is an error, I cannot be relieved.
Dose someone knows how to fix this error?

thank you