Backtracking with minute data

Dear SAM team,

when setting up backtracking with a minute data file I am seeing strange behaviour of the energy output and the tracking angle. For some month it start at fixed maxiumum angle in the morning until it jumps to cero and than turns back slowly to max angle, remains there before noon and going back to cero during midday.

Please find the screenshots attached.

I would appreciate if you can explain the behaviour and maybe point out a solution to avoid the jump in production.

Thanks a lot
Marius