Saves with an invalid last generated RefNum can be loaded

Windows 10, GOG version of Morrowind GOTY, playing OpenMW dev build (7f117a28).

After reporting to Caius I placed a bunch of items from my inventory (Journal of Tarhiel, Scroll of Icarian Flight, Directions to Caius Cosades, equipment, etc.) on the floor and shelves in Caius' room. I took the boat from Vivec to Sadrith Mora, after doing a quest on the other side of the map I returned to Caius' house and nothing I had placed was present there anymore. Throughout that time I had saved and quit at some point, so it wasn't all in a single play session if that's relevant. What could have happened here?

All my loaded mods from openmw.cfg, just to show that it's likely not a mod interaction:

data="C:/Games/Morrowind/Data Files"
data="C:/Games/OpenMWMods/Patches/PatchforPurists"
data="C:/Games/OpenMWMods/Patches/UnofficialMorrowindOfficialPluginsPatched"
data="C:/Games/OpenMWMods/Fixes/GreyedOutDialog"
data="C:/Games/OpenMWMods/Fixes/MeshFix"
data="C:/Games/OpenMWMods/Fixes/CorrectMeshes"
data="C:/Games/OpenMWMods/Fixes/CorrectUVRocks"
data="C:/Games/OpenMWMods/Performance/MorrowindOptimizationPatch/00 Core"
data="C:/Games/OpenMWMods/Performance/MorrowindOptimizationPatch/01 Lake Fjalding Anti-Suck"
data="C:/Games/OpenMWMods/Performance/MorrowindOptimizationPatch/03 Chuzei Fix"
data="C:/Games/OpenMWMods/Performance/MorrowindOptimizationPatch/04 Better Vanilla Textures"
data="C:/Games/OpenMWMods/Performance/ProjectAtlas/00 Core"
data="C:/Games/OpenMWMods/Performance/ProjectAtlas/01 Textures - Vanilla"
data="C:/Games/OpenMWMods/Performance/ProjectAtlas/hotfix"
data="C:/Games/OpenMWMods/Fixes/RopeFenceFix"
data="C:/Games/OpenMWMods/Fixes/FamiliarFaces"
data="C:/Games/OpenMWMods/Fixes/swayland"
data="C:/Games/OpenMWMods/Fixes/SiltStriderAnimationRestored"
data="C:/Games/OpenMWMods/Fixes/NoMoreStageDiving"
data="C:/Games/OpenMWMods/Fixes/TimeScaleChange"
data="C:/Games/OpenMWMods/Fixes/WeaponSheathing"
data="C:/Games/OpenMWMods/Performance/MorrowindOptimizationPatch/02 Weapon Sheathing Patch"
data="C:/Games/OpenMWMods/Fixes/SameLowPriceFix"
data="C:/Games/OpenMWMods/Fixes/DynamicDistantDetails"
data="C:/Games/OpenMWMods/Fixes/DistantSeafloor/00 Core"
data="C:/Games/OpenMWMods/Fixes/DistantSeafloor/01 Patch for vanilla Solstheim location"
data="C:/Games/OpenMWMods/Fixes/CantonsontheGlobalMap"
data="C:/Games/OpenMWMods/Tools/DeltaPlugin"
content=Morrowind.esm
content=Tribunal.esm
content=distant_seafloor_2.00.esm
content=Bloodmoon.esm
content=Patch for Purists.esm
content=distant seafloor bloodmoon patch.esp
content=Unofficial Morrowind Official Plugins Patched.ESP
content=Patch for Purists - Semi-Purist Fixes.ESP
content=Dialog_Saved.ESP
content=NoMoreStageDiving.ESP
content=Silt Strider Animation Restored.ESP
content=Patch for Purists - Book Typos.ESP
content=Lake Fjalding Anti-Suck.ESP
content=chuzei_helm_no_neck.esp
content=Cantons_on_the_Global_Map_v1.1.esp
content=HM_DDD_Ghostfence_v1.0.esp
content=HM_DDD_Strongholds_H_v1.0.esp
content=HM_DDD_Strongholds_R_v1.0.esp
content=HM_DDD_Strongholds_T_v1.0.esp
content=TimescaleChange.omwaddon
content=delta-merged.omwaddon