I think the screenshot says it all:
(https://drive.google.com/uc?id=1VHXGsanqI-obMKNsVjgA-nHUzfhSeqQP)
Appears in 120.2.2 with pak64 120.2. Also appears in r8387 nightly. Savegame attached. There's only 1 city.
Forget to add, both drive_left = 1 and signals_on_left = 1.
Have fixed it locally, but svn server seems to be down.
should be fixed in r8397 & 8398.
Confirmed fixed. Thanks! Had to download the nightly from https://farm.openttd.org/browse/SIMU-NIGHTLY (https://farm.openttd.org/browse/SIMU-NIGHTLY) because https://nightly.simutrans.com/en/ (https://nightly.simutrans.com/en/) is out-of-date for some reason.
thanks for the reply