I'm using an Apple USB-C to Thunderbolt 2 adapter on the 2018 MacBook Pro and a Mini DisplayPort cable (not a Thunderbolt cable) to the iMac. It doesn't work. The Mini DisplayPort cable and Target Display Mode works great with a mid-2014 MacBook Pro (with Thunderbolt 2 ports). Would a Thunderbolt cable work? Has anyone successfully used a 2018 MacBook Pro in Target Display Mode to a late 2019 27" iMac? If that combination doesn't work with Target Display Mode, is there other software or hardware to display the 2018 MacBook Pro screen on a late 2009 27" iMac? Thanks in advance.