Hi, thanks for sharing this issue.
Shared projects essentially get rolled into the same assemblies once the compiler is done with them, so probably there is a code structure involved here that the compiler is creating that the new optimised mode just doesn't know how to handle.
Is there any chance you can isolate this problem with a sample solution that you can share with me? If I can reproduce it here, I should hopefully be able to promptly fix it. You can upload code in ZIP form through the
contact form.