Lotus Sametime window disappears randomly

Hi

I am new user of Mac. Currently on 10.9.5 and using IBM Notes 9.0.1.

I need Notes to access my office mails, hence please dont suggest another software :-)

Notes comes with an included sidebar sametime window for chat. When I select to chat with a colleague, it opens a new window to chat.

Now when I minimize this chat window, randomly one of the window disappears.

I have tried to use "switch within app windows" Command + ~ . I can navigate thru other chat windows (of sametime) but not the random disappeared one.

I have tried in the dock to option click and check the open windows. It shows the missing one but when I try to click it, it does not come.

Any other options to try?

Only way I am currently doing is force quit the Notes application (it warns that a sametime window is open😠 ) and then reopen Notes

I have now disabled the dock preferences to minimize the window to single application. But this is annoying as this clutters the dock.

Any other suggestions?

Thanks