Cell colour and table format seems to be off in exported PDF or Word document

Bug report

Environment

Confluence is upgraded from 6.2.3 to 6.12.1.

Steps to Reproduce :

1. Create a page in Confluence
2. Create a table along with contents with few cells highlighted in colours
3. Prior to Export, verified Source View of the page which appears to be in-line with the actual Confluence page

Expected Results
Exact replica of the confluence page where table is not overlapping and cell colour is displayed

Actual Results
During export, cell colour has disappeared and tables are slightly overlapping

Workaround

No known workaround