Raft causes purge block to be on different layer

I’m seeing some strange behavior on the filament usage and purge tower when using a raft: https://share.canvas3d.io/projects/8038a...

I would have expected the black ABS to be used exclusively in the raft, but it looks like there is an extra transition or two, possibly with interfering lines being deposited.

Using the raft also seems to put the purge tower and print layers on different Z heights. Very strange

Are there any settings I’m missing to simplify the raft material usage?