timeline disappearing when open application

currently having a problem here with the timeline in premire pro, every time when i launch the application, i open the project and have to manually add the timeline into the project and when i close the application and reopen it, the timeline isnt automatically there. what would be causing it to not be there everytime. 

as you see in the clip i shared. i tired my best to explain in the best way incase the video wont load or not working.

personally i think this is a bug or something is turned off in the setting, not pretty sure

Thanks