Ah, ok. Looking forward to a fix so I can continue making my 1.13 maps.
Suggested Fix: Allow quotations when accessing JSON objects?
i.e.
/scoreboard objectives add <objectiveName> "minecraft.custom:minecraft.jump" <displayName>
in previous versions using HandItems:[{id:"minecraft:stone",Count:1b},{}] worked even with the colon there.
Thanks for fixing this!