This is non-artist/title specific Black Box/Breakage income (such as audit settlement monies, unclaimed monies, leftover amounts from an unrecouped advance..…etc) from partners. This income will have been paid to Kobalt based on the usage % share of its catalog on each of these particular DSP services. We then complete a pro-rata calculation based on your performance compared to other AWAL/Kobalt clients on that specific music service.
Blackbox income is generally only paid around once a year and will be shown on your PDF statements as an adjustment. The description will be along these lines, from a recent example, "Spotify Blackbox October 2016".