.pdf file doesn't load data

Hi,

One of my reports has 64k records on SSRS report. when I export to .pdf file format .pdf file has 359 total pages. Recods loads nice until page no 121. from page 122 couple pages are blank and then records comes back. To make it more complex report shows data which is group by box no. so till page 121 everything is good. after that one group by records are blank and next is visible then group after that is black again. so it shows data for alternate groups. 

I tried importing report to word file and  it loads all the data sucessfully. So, I don't see any data issues.

Business needs report in .pdf  so, I would love to know if anyone knowsthe solution to it! Thanks in advance.