Worked for company that was bought by MS. During the acquisition period, I was working for 3rd level enterprise support and were main contact for escalation of issues from our OS X users and MS. And yes, it never worked. Higher up guys where patting themselves on the backs for migrating to Lync and now it was So Well Executed while we in the actual client interface where left to deal with abysmal (platinum) support, private hotfixes, fixes what worked at one release and didn't on newer ones and all sorts of crazyness.

The "reason" that was said to be the issue was "our internal routing between the sites" and Yeah, pretty much every issue we had never manifested it worker was at home and used home connection or used cellphone client and gsm operator for data.

But yeah, fuck Lync. Worst gig ever. One reason why I think rebranding Lync to Skype for Business made sense: let's fool someone to buy it by letting them think they where getting same tech as real Skype, not just same shit with different name.