RE: XPS 9550 not working with TB15 Dock
***ATTENTION TO EVERYONE***
After talking to a couple different reps, they're updating the BIOs on all devices using the thunderbolt port and it should fix the issue with the TB15 on the 9550. Supposedly end of JUNE 2016. No promises of course but from what I heard, it looks like it will be the fix. Not sure it is a device issue with the dock like some claim. At least that isn't what Dell is saying on my end. It is a BIOs issue. And they stopped selling because they didn't want anymore backlash. The TB15 will be on the market again once the BIOs update comes out.