Try doing a quick "cheat"
Right-click on the layer you want to move into your main layout.
Select "Duplocate Layer" and then change the "destination" to the main layout's name.
This duplicates the whole layer without dragging and dropping.

Not sure why, but this method has always been faster (even before computer upgrades).
Good Luck, and let us know if anything helps.

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Colleen in Friendly Manitoba...
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