relative Mode switches automatically to flexible mode

Hi community,
im using a DVS setup with two timecode vinyls and external mixer in Cross 3.3.1 (64 bit) on my Macbook Pro.
The problem is following: Sometimes during a track the software switches automatically from relative mode (the mode I want to use) to flexible mode, so I loose control over the track via timecode vinyls.
Before it switches automatically a tiny little warning sign appears in the corner of the relative mode button. After it switched to flexible mode, pressing the relative mode button won't help anymore. Also, the software changes the BPM while switching in flexible mode.
I already tried checking/unchecking the checkbox "switch mode automatically" in the vinyl/cd settings, it wouldn't help.
This is a major problem for me and I have not figured out yet what could be the reason behind this.
im using a DVS setup with two timecode vinyls and external mixer in Cross 3.3.1 (64 bit) on my Macbook Pro.
The problem is following: Sometimes during a track the software switches automatically from relative mode (the mode I want to use) to flexible mode, so I loose control over the track via timecode vinyls.
Before it switches automatically a tiny little warning sign appears in the corner of the relative mode button. After it switched to flexible mode, pressing the relative mode button won't help anymore. Also, the software changes the BPM while switching in flexible mode.
I already tried checking/unchecking the checkbox "switch mode automatically" in the vinyl/cd settings, it wouldn't help.
This is a major problem for me and I have not figured out yet what could be the reason behind this.