xf:dispatch using @while to xf:action containing xf:insert and xf:message[@level="modal"] causes 100% CPU

The attached form has two triggers that insert a number of nodes into a nodeset via a xf:dispatch element that has a @while attribute.

The first trigger triggers an xf:action that just does the insert and works fine. The second trigger triggers an xf:action that does the same insert as the first trigger but this action also contians an xf:message element with a @level="modal" attribute. Using this trigger, the message is never shown and the CPU is then constantly at 100% (shown in the task manager) The inserts never happen.

CPU is not 100% if the messages @level attribute is "ephemeral" but then the message is still not displayed.

Instructions are on the attached form.