I had the exact same problem which was being experienced by some of my clients with them even threatening to sue our it support services for lose of business due to this issue. Microsoft support were totally useless on all fronts just referring me to a number of support articles which i obviously tried countless time before even getting in touch with them and lets just say that i personally found their support disappointing and pathetic, but in regards to your problem. I found a solution that did work after some playing around on my side.
thre
What worked for me was to go through control panel, then go to internet options and then select "change security settings". From there select the security tab add the source location of the files to either Local intranet or teh Trusted sites location. ( I then also reduced the security level of these sources to the lowest possible settings (not sure if this was necessary or recommended but i was just experimenting). The files have since been able to work without the blocked macros restrictions.
I am still playing around with this but since doing this my clients are able to work normally again which is what is important. I will be pushing this setup through group policy on our various clients servers to prevent any further problems from occurring in the future and will try update on how this goes. But for now, this is the only solution that worked.
If anyone else can try this and update, please do share.
Microsoft, i don't need to hear from you. You were of absolutely no help in anyway so i'd rather take suggestions from the people that actually help....your affected customers ( the ones you don't care about)