Popping/clicking Clarett 8PreX

[hirundos]

My Macbook Pro (specs below) running PT 2018.4 paired with the Clarett 8PreX was used on a location recording. I listened back to the tracks and on one of the tracks in a few places, there are some noticeable click/pops. I have come across this while running tests with this setup in the past, but it seemed to go away with a focusrite firmware and PT software update. They would present themselves while monitoring, too, in the past, not just while actively recording. Looks like it didn't go away. I had to run sections through iZotope and remove them manually. Ouch. Screenshot of the clicks in iZotope as an attachment. They're the really obvious thin vertical stripes across the spectrum.
Any idea what it could be? I need this to be a solid recording setup.

Macbook Pro (13-inch, 2016, Four Thunderbolt 3 Ports), 2.9 GHz Intel Core i5, 8 GB 2133 MHz LPDDR3. MacOS Sierra 10.12.6.