Paginated Report - Stacked Chart - Adding a marker...

I have built some stacked charts in Paginated Reports. Everything is working well except that for some inexplicable reason, on data labels with values that are small (between 1 and 5), the report seems to insert what, to me , looks like a marker. However, even this is not inserted consistently where it inserts it at certain points and not at others where the “small values” are displayed.

I have kept this chart very simple and there are no markers enabled. I have checked all parameters but I cannot identify the option to suppress this “feature”. I attached a pic for to illustrate the issue.

Any help is highly appreciated.

Kind regards