Image status change flashes/flickers in New Adobe Captivate 12.6

I am using the new Adobe Captivate 12.6.0.63 on my Mac with Sonoma 14.4.1

On some slides I have added image status changes which are triggred by timeline bookmarks.

On one slide e.g. each status change reveals more of the image (which is a process chart with 4 steps) while the narratior voice explains the process steps. In total there a 4 status changes for the image.

However when I publish the course to SCORM and play it in a LMS or Scorm Cloud then you can seea short flash/flickering with each image status change. I am using pretty small png images, so the size can't be the reason. When I delete most of the slides and publish the course to SCORM with just 3-4 slides, then the image status changes do not cause a flash/flickering. 

I had also contacted the Captivate support, but they could not help me. The gave me the advice to rebuild the slides in a new course, which I did. However the flashes were the same.

Anyone might have an idea what I can do?

Best wishes and thank you Marc