Problems with lazy loading in containers and tabs

[ZbigniewK]

I have mashup, where I have 1st container with a button, second with tabs, and in first tab I have mashup container with mashup AAA inside. Do not want to present this internal container, until button is not pushed.

Case 1. I set tab ptcs-tabset-6 # 1, lazy loading true. I set connection of clicked button to Load Container. I open mashup... and see inside of mashup AAA  just after I've loaded mashup, without clicking button. 

Case 2. This same structure, but this time tab ptcs-tabset-6 # 1, lazy loading false (unticked), container 3 lazy loading true, ptcs button 5 connected with Load Container for container 3. 

This time it works perfectly.
So I create similar structure inside my already existing mashup. Do it with this same mashup.

I load mashup, click button... and I see tabs, but do not see mashup from mashup AAA. Logs confirms, service called by mashup AAA OnLoad is also not started. 
Why case 1 is not working? 
What can be wrong with on mashup already existing?
TWX ver 9.5.1-b359

[DanZ]

From Using Lazy Loading in a Mashup (ptc.com)

"Lazily loaded containers within the Tabs widget are automatically loaded, unloaded, and reloaded when you switch to a tab that is configured for lazy loading."

Since the Tabset widget will automatically select one tab, it will trigger the event to actually load the (lazy load) mashup inside of it. But I am not sure about the behavior in your existing mashup.