FT-847 Tracking-Bug with PTT

Hello together,
today I tried on RasPi 4B GPredict with my 847,works fine so far, but on U/V-Sats there is a quirk when TXing.
When Tracking is enabeled on a, Sat in U/V (e. g. AO-07, AO-91…) and pressing PTT, the TRX stays in transmitting for two seconds or so, and then falls back in receiving mode although PTT is still pressed.
This behaviour doesn’t occur in V/U-Mode, like on RS-44.
Any ideas to fix that? :thinking:
73, Ben, DL4ZAB