That issue seems to be fixed! I still seem to get some deadlocks and I have isolated another bug: in some cases a train reversing at a stop will have its platform unreserved, leaving it reservable by other trains.
.sve: https://simutrans-germany.com/files/upload/Broken_time_interval_2.sve
Thank you for that - I have split this from the other topic in order to keep proper track of the reports (one per thread only). I think that I have managed to fix this - would you be able to re-test? I should be most grateful.