The issue is the same. You are adding pages from the next report when the rendering of the first one is not finished.
Please, add a line of code to the each for statement that will log the report and page number.
You should see that they are being added in the wrong way.
And replace the next line
Code: Select all
reportMerge.renderAsync();
with
Code: Select all
reportMerge.isRendered = true;