Hey. DCs can be buggy, but there are best practices and work arounds. I would be interested in seeing some of the DCs that had problem behaviour, or a recreation of the problem. My workflow is all DC and I copy and scale instances all the time and still get accurate reporting. Most often I copy and scale these lumber DCs, making unique as I change use case, ie joist, blocking or ledger.
The Scale Definition attribute in the 2x PT is a custom one I added as a personal extension, originally I used a material scaler as in the 2x Framing. The Scaler will make each instance unique when scaled, also any direct editing of geometry in a complex DC (has 1 or more children) will break the LenXYZ attributes. Resetting the Nominal LenXYZ attributes can correct that:
Here is a helpful list of DC Gotcha’s:
And here is a DC reuse post:
For the best answers on best practice workflow questions search @pcmoor Philip’s posts, he is the GOAT on DC how to. Not sure if any of this helps but without specific DC cases to look at it’s really hard to nail down what is happening with your DCs.