I am an architect managing 8 different macs each with os 10.3.8 and VW 11.5. I can confirm this problem happening on them all.
We use workgroup referencing a lot in our office and if i want to copy select lines from a referenced layer to the 'live' layer I can no longer shift-click and select the lines i want. It simply won't pick a second line up. Bizzarely you can still draw a selection box around the objects and highlight them all and you can also alt-select multiple objects, but not specific ones. This only occurs in layers that are referenced, shift-clicking still works as normal in a normal 'live' layer.
This is proving to be particularly irritating at the moment because there are a great deal of arcs on the drawings we're doing at the moment, and even when they are not filled, alt-selecting anything inside the arcs will also select all the arcs it sits within! Thus a lot of time-consuming individually selecting and copying lines.
Please help this is driving me mad!