I just tried it out on a new document and it works fine for me, so maybe your document has glitched. Try exporting to IDML and opening that.
I see you have a lot of styles. Is it possible you are applying a different style to the fourth paragraph at that level? Also, try right-clicking on the paragraph and see if Continue Numbering is in the contextual menu. If it is, the paragraph is not currently using the next number (or letter in this case).
Edit: Check the Level attribute for your styles. The A, B, C paragraphs need to be Level 1, or at least a higher level than the numbered paragraphs.
Can you lest us know if TOPIC A, TOPIC B have one style applied and TOPIC C has another style applied?
If yes, maybe the style "TUES ROUND TABLE CONTINUE" has been defined something like this..
If yes, then you need to create Lists in order to continue the numbering from the style of TOPIC (A&B) to style of C...
Normal behavior if A. and 1. are on the same level!