I found that longer, larger flights can trigger the end-script to hang and never recognize the mission has ended, losing all progress. This was with the Invasion of Iran setup on RC9.
After 2 normal cycles of mission planning in Liberation's GUI, run mission, exit, tally results, I launched a large offensive with the ground forces from one airbase commanded to 'breakout' in the Liberation settings. I did change loadouts for my flight in mission editor, but that's it (and hasn't caused issues on previous missions).
On exit from that hour long mission, the tally presented by Liberation's info screen appeared correct (some 500+ weapons fired, 35 aircraft, 178 ground units destroyed). However it still showed "Mission is being played." The DOS screen for the Liberation engine was still scrolling with tons of info, but when it eventually stopped, the "Mission is being played." message stayed in the GUI and never changed to 'Accept results.'
Seeing as the info was probably lost anyway, i tabbed back into DCS, restarted the mission, and immediately exited. The Liberation engine then correctly caught and completed the post-mission processing and showed 'accept results.' Of course, the results were now 0/0/0.
Another user, Chicki, claims to have seen the same thing occur, I've asked for more details - crosspost on ED DCS forums (http://forums.eagle.ru:8080/showthread.php?p=4437934&posted=1#post4437934)
From the log generated, it appears to have hung on a crucial step before finishing processing. Here's the relevant bits if anyone is seeing this issue - key points marked with ### ###
2020-07-28 22:51:21,415 :: INFO :: {<class 'dcs.vehicles.Infantry.Paratrooper_RPG_16'>: 7, <class 'dcs.vehicles.Infantry.Paratrooper_AKS'>: 49, <class 'dcs.vehicles.Infantry.Infantry_Soldier_Rus'>: 32, <class 'dcs.vehicles.Armor.MBT_T_80U'>: 8, <class 'dcs.vehicles.Armor.MBT_T_72B'>: 4, <class 'dcs.vehicles.Armor.MBT_T_90'>: 2, <class 'dcs.vehicles.Artillery.SPH_2S19_Msta'>: 6, <class 'dcs.vehicles.Artillery.MLRS_9K57_Uragan_BM_27'>: 8, <class 'dcs.vehicles.Armor.APC_BTR_80'>: 2, <class 'dcs.vehicles.AirDefence.SAM_SA_13_Strela_10M3_9A35M3'>: 1, <class 'dcs.vehicles.AirDefence.SAM_SA_10_S_300PS_SR_64H6E'>: 1, <class 'dcs.vehicles.AirDefence.AAA_ZU_23_Emplacement'>: 3}INFO:root:{}
2020-07-28 22:51:21,415 :: INFO :: {} INFO:root:{}
2020-07-28 22:51:21,415 :: INFO :: {} On Debriefing update <userdata.debriefing.Debriefing object at 0x0000025346DA9160> ###Script appears to have halted here###
INFO:root:-------------------------------- ###retrigger mission by launching mission and immediately exiting###
2020-07-28 23:00:51,009 :: INFO :: -------------------------------- INFO:root:Starting Debriefing preprocessing
2020-07-28 23:00:51,011 :: INFO :: Starting Debriefing preprocessing INFO:root:--------------------------------
2020-07-28 23:00:51,011 :: INFO :: -------------------------------- INFO:root:[]
2020-07-28 23:00:51,011 :: INFO :: [] INFO:root:[] 2020-07-28 23:00:51,011 :: INFO :: [] INFO:root:[]
2020-07-28 23:00:51,012 :: INFO ::[] INFO:root:[]
2020-07-28 23:00:51,012 :: INFO :: []
###snip to area with final results###
INFO:root:{} 2020-07-28 23:00:53,498 :: INFO :: {} On Debriefing update <userdata.debriefing.Debriefing object at 0x0000025346DAC4E0> ###point where script hung last time###
INFO:root:Finishing event Frontline attack #script continues###
2020-07-28 23:01:09,461 :: INFO :: Finishing event Frontline attack INFO:root:Commiting mission results
2020-07-28 23:01:09,463 :: INFO :: Commiting mission results Compute frontline progression for : Havadarya to Lar Airbase 41 22 0 0 Havadarya won ! factor > 0 Compute frontline progression for : Bandar Abbas to Jiroft Airport 26 8 0 0 Bandar Abbas won ! factor > 0
INFO:root pass turn