RM9 Descendant Chart box size error

What setting have I messed up to get this result in Ancestor and Descendant Charts? The boxes seem to have zero height and I surely can’t find that setting



Rather than me guessing:

Some users have reported seeing that every now and then. One person mentioned if they open RM and wait a bit, before trying to generate the chart, that it works for them. You could try that. For now, the exact cause is not known.

Bizarre, it reset itself! Left RM open overnight and it is fine in the morning when I rerun the report.

Thanks for the responses.