5E Charactermancer Custom Patron missing from Multiclass

Hello, While doing some testing for character builds, I discovered that the "Custom" option for adding Warlock Patrons is not available when adding a multiclass level, though it is available for a clean character. Below image was taken from a fresh install of Chrome Version 83.0.4103.106 (Official Build) (64-bit) with no extensions installed, however a similar result happened while on Firefox 77.0.1 (64-bit) with various non-Roll20 extensions installed. (Note that I am not making a Dragonborn Barb lock, I just put in random selections to recreate the issue.)

Just tested with the PHB & Xanathar's to make sure it isn't a SRD issue. "Custom" is still not available for multiclass, as you have pointed out. However, you can proceed with leveling up your character without selecting a Patron at all - just leave it blank. Add your custom Patron powers to the traits section once charactermancer is finished. There's effectively no difference between selecting no Patron, and selecting custom Patron, either way you still need to enter your custom content after charactermancer is finished.