An engineering team found some 20 Sorium Harvesters in ruins. I sent a freighter TG there to pick them up. It went fine until the next-to-last batch of 5. I had to re-issue the order for the TG to unload it, because
14th September 2079 07:12:16,Sol,Cargo Task Group failed to Drop off Sorium Harvester on Earth. Please reschedule the orders for this fleet
The TG DEFINITELY had the Harvesters in its holds. When given the order a second time, they unloaded without a glitch.
The last batch proved. . . strange. When they were loaded and the TG departed (in fact, I noticed it when I were issuing orders to pick up some engines found in the same ruins) there were 0xSorium Harvester left. Out of curiosity, I disassembled one. Got a "No new tech" MSGBox and . . . I now had -1 (!) SH on the planet. I scrapped it and. . .
6th November 2079 01:15:01,Groombridge 34,-0.7x Sorium Harvester scrapped. Salvage from scrap: Wealth: -12.6. Duranium: -9.5 tons. Boronide: -3.2 tons.
Unfortunately I didn't think to look at mineral stockpiles and/or wealth before the scrap.
UPD: Well, i looked at the Minerals screen and it really had -8 (after a couple of months - there is a deposit and a Automine) Duranium. It'd be logical to assume that the rest also got deduced.