Hello Sayontan ,
In "Edit Page" I inserted the following short code for a Picasa public album into a page in "text" edit mode:
[gallery type='picasa' user_id='105404946895869986719' album='DeckGallery']
The album would not appear after repeated "Update" attempts. I finally found success after I toggled between "text" and "visual" edit modes.
I have not been able to repeat this phenomenon on other pages and it could very well be an effect from some other change I made but I thought that I would share this experience just in case it may help someone else.
Thank you for all of your effort to produce a great plugin that works with WordPress Ver 3.5!