Power Window Issue

Need some help with a power window issue I've been having.

Just replaced the front passenger window motor/regulator on my 99 Buick Regal. The window will roll down, but not back up.

Here's what I've tried:
Different switches on the front passenger door.
Checked relays.
Checked wires at front passenger door, found no issues.
Checked voltage at front passenger switch. Good in both directions (positive and negative polarities).
Front driver master switch will not operate the front passenger window in either direction. Will operate all other windows fine.
Front driver master switch is grounded.

I'm stumped. Do I have a bad master switch? Is it possible that the master switch could be bad on just the front passenger window switch alone? Any help or guidance is appreciated.

Had almost the exact issue on a dodge ram. Master switch issue. Found new one on ebay with lifetime warranty.(after market) Guy had an OEM, but only 90 warranty. Got the lifetime, had to exercise warranty twice. Guessing design flaw. Because all the switches on the master are soldered to the circuit board, couldn't replace just the switch. Suspect issue is with the child isolate switch.

You have an open wire or bad master switch......it's probably an open wire in the "A" pillar on the driver's side, since the driver's side is opened way more than the passenger side(I'm talking about the wires that go from the "A" pillar through the rubber loom covering to the LF driver's door).....

You can verify this with a test light....disconnect the harness to the right front passenger switch....with the ignition key in the on position, attach the test light to the harness at the term B(dk blue), power, and the term A(light blue), ground thru master switch, connectors....light should be on.... now, switch the the test light lead from terminal A, to term E(tan), ground thru master switch.......the test light should light...if it doesn't, and you have checked your master switch, you have an open tan wire to the master switch.........

You can check this by leaving the passenger harness connected to the test light at terminals, B and E.....now pop out the driver's side master switch...leave the harness connected to it....get a jumper wire and attach it to a good ground.....now back probe the master harness connector, C1, at terminal C, the tan wire, with the other end of the grounded jumper wire.......if the test light at the passenger harness now comes on, you have a bad master switch....if it doesn't, you have an open wire.....

Thanks for the quick responses and good info. I picked up another master switch from the junkyard, still the same problem.

However, I did pull off the rubber loom in the driver's door. I did not see any broken wires, but I did notice this (see picture below) when I pulled the connector apart.

It looks like there is some burnt damage on the terminals of the black w/ white stripe wire. Would this cause the problem I'm having?

I will try the test method and report back.