All Perpetua keyword campaigns are launched with 3 ad groups, one for each match type. In most campaigns, you will see the same number of targets in each of these ad groups.
However, in a keyword boost you will likely see incomplete ad groups. This is due to there being no keywords of that match type in that keyword boost, and is expected.
In the below example we can see an active keyword boost, containing 2 EXACT match keywords:
