Is there a limit on the number of regions I can mark in a clip?

Having worked on a dozen small Kdenlive projects so far, I'm (still) having some issues, so I'm asking here for help. Maybe one or another issue may actually be a bug, but before filing bug issues, I want to make sure that the problem is not me in fact. For your information: I'm using the most recent kdenlive compilations from sunab's bleeding repository on a Kubuntu 12.04 installation.

Now for my problem: usually my raw footage takes can be up to several minutes, say a five minute take of a slow dive through an underwater landscape. When reviewing the raw material I want to mark several regions in this clip for further reference. However, while I can mark one, two, or sometimes even three regions one after another and add them using Ctrl-I, this suddenly stops working after only few regions. Sometimes I even can't add any region using Ctrl-I. What am I doing wrong?

Any help greatly welcomed. And many thanks for the great work of Kdenlive!
-- TheDiveO