I have no personal knowledge of the issue. But I have done 25 years of construction litigation, so I'm making some guesses based on that and based on what was written above.
1) Berklee might be the "developer", but it isn't the general contractor.
2) The subcontractor may have had a financial failure, and/or is not being timely paid by the general contractor, and/or has done a faulty installation, and/ or has used faulty materials.
3) Berklee will make a claim on the performance and payment bonds (if it has been wise enough to require them), and if applicable, the manufacturers warranties, and no one will want to compromise claims against these sureties by jumping in and starting work on windows until the cause of the problem (see #2 above) is identified and agreed upon by as many parties as is possible.
Or something like that.
In other words, this is a typical construction project.