I have tested this myself and found this problem to be 100% reproducible in TBB 4.5.3 for Windows XP but impossible to reproduce in Linux or Windows 7. Opening 3 to 4 tabs in the latest TBB for Windows XP does seem to break the Tor circuit view however it is only when the new tab is on a different website. Opening multiple tabs on stack exchange or startpage.com will show the tor circuit as the same circuit for each tab that is on the same site. But for example opening stack exchange in tab 1, startpage.com in tab 2 and youtube in tab 3 will likely break the circuit view for tab 3.
Can you confirm that you are using Windows XP or if not, can you tell us which OS and TBB 4.5.3 version you are using?
To answer the question, The TBB should always use a circuit for all the tabs, and I think it is still using a circuit even when it is not displayed in circuit view. Here's why:
When I tested the example above I ended up on Youtube FR and the webpage was displayed in french (I am not in a french speaking country). So it seems safe to say that I was using a tor circuit and that my exit node was in France. I also broke the circuit view again after opening 4 tabs. To try to test my tor network settings I opened a further tab and entered about:tor in the URL bar to get to the tor start page. I then clicked the 'Test Tor Network Settings' link and got the congratulations page and an ip address in a different country to my own, even though I couldn't check my tor circuit using the circuit view. I could also read about my exit node in the atlas. You can also go to websites that tell you your ip address and make sure that they don't display your actual ip address if you want.
So the good news here is that opening multiple tabs in TBB does not seem to break tor but on Windows XP (and possibly others) it does seem to break the circuit view.
If you can find evidence that you are not using a tor circuit after opening multiple tabs then this needs further investigation. So I recommend checking your tor network settings is a similar way to the way I described above.
Do remember that the tor circuit view was only brought in for TBB 4.5 and so is still very new, it is possible that there are some issues with it. I have noticed problems with the Windows XP circuit view since the circuit view was introduced. I think 4.5.3 is the first version that displays any circuit view whatsoever whereas the other operating systems have been reliable from the beginning.
I havn't found anything online that explains the problem with the circuit view but provided that it is not stopping TBB from creating circuits it's not really something to worry about.
For anyone interested I tested using Windows XP (32 bit) Windows 7 (64 bit) Fedora 22 and Debian 8 (both 64 bit) and the latest (verified) TBB for each.