A dropout occurs when the writing speed of the drive is slower than the recorded data coming in. The Take remains as is in the drive, only some miliseconds/seconds within the take should be lost when a dropout occurs.
Each take is a folder(TakeXXXX) and there could be multiple multichannel wave files inside the Take folder depending on how long your take is. Each wave file has information of all your recorded tracks. For example Take0001(0001).wav would have the first 10 minutes of all your 24 tracks and Take0001(0002).wav would have information from minutes 10-20, and so on.
uTool helps you stitch these wave files and split them into mono wave files.
Coming back to your problem, it seems that something definitely went wrong. It is hard to understand why there is no Take0001 in your case, if that is what you saw during recording.
I would at first request you to check the following, for not having any problems in the future
1. You are using the latest firmware for the uTrack24.
2. Make sure that the drive is formatted using uTrack24 before you start using it.
3. Make sure you are using a drive and not a stick for recording
4. Place a soft cloth below the drive(to avoid dropouts) if there is too much vibration at the gig.
When you say that you have multiple takes, do you have multiple TakeXXXX folders? Pressing the record button, while a recording is going on creates a new take without losing any recording data. Did you do that by any chance?