It seems blocks created in another than "0" layer inserted into an other layer will always be linked with the one they were created in. So complicated... It's advisable to create blocks in Layer 0 only to avoid these complexities.
I have found out you can use "Edit the active block in a separate window" to change the layer of the block's entities from the one they were created in to the one they were inserted into. So if you desperately need it you can go that way.
I don't know that I'd say it's complicated. Either you have a block that can live in whatever layer you want *or* you have a set of standard layers and use those in your block. While it may not always be intuitive at first I don't know how else it could be organized.
Have a read through the User Guide - Using Blocks for some more details on blocks. In particular, it offers some information on why creating blocks on layer 0 is useful when using blocks you've created in other drawings.