Hey, I was able to fix this by changing the DVI setting on the EX90 from Auto to Analog.

I would love to get this resolved. Being a mac user with an Ex90 in my office is very frustrating! I can connect my iPad just fine but not my MacBook. I have played with resolution settings to no avail. Would definitely be willing to testEmmar@ecboce...

I having the same issue.  EX90 will not see my Macbook but Macbook sees the EX90.  Did you find a fix for this?