You have to check your paragraph styles. First I would look, on which style depends your style, the parent style. Maybe that you have accidently changed the parent style before you created your figure style, If this does not solve the problem, you should look which other styles may be affected.
Be aware that not all numbered list paragraphes may have a visible number!
Do also check, if you have changed other paragraphs without applying any style but affecting the numbering. Might happen. They sould have a + after their name if text is selected.
Figure numbering treated the frames based on the order in which the frames were created—not the order on which they appear on the page.
Make sure that the frame created started from the first page.
If that would be the problem here, Colshvar would see the missing numbers connected to other images in the document. So I suppose that this is not the case here.
Thanks Willi, you found the solution. My caption style originated from a MS word list style which created some interference. I had duplicated the Word style to create a new customized one. And although the new style had no parent style and although it showed the desired parameters, it was still counting 30 I-don't-know-what. Something must have happen in IDesign code after importing my Word text. Thanks again.