Thank you all for the help.
Walt Farrel: I have turned ligatures off (Text>Ligatures>Use None). And "Export Settings>Subset Fonts" checkbox unticked. The problem still persists. Maybe I have turned off ligatures incorrectly. Is there another way to turn of ligatures. I do not need ligatures.
Paul Mc: Gurbani Akhar Heavy font attached. Since you do not have this issue, there must be some setting that I could set to eliminate this problem. Have you any ideas.
The problem this issue created is that the PDF created will have search issues. On search any word with "ti" will not show up in the search result. This is not good especially since I am distributing the PDF and the reader might search a word and miss out on words with "ti" in them. That is how I found out the problem.
For me this issue is a big problem. A resolution is really appreciated. Further I wish to add that this problem did not exist previously ... I checked an exported PDF I prepared in March this year. So it must have come up in the latest update.
GurbaniAkharHeavy.ttf