My problem is, that I lately cannot complete any "deliver X item" side quests, because the option to give the item to the people is simply gone.
- "Retrieve a custom PMm from a fallen squad leader in the Swamps"
I got the item (a bloodsucker was there), went back to the stalker, but no "here is your item" option listed
- "PDA with secret information" (for Duty)
Same, got the item, went back to Duty base, talking to the man marked yellow in the map, but no option to give him the item.
What can I do? I've tried dropping the item and picking it up again, saving, reloading, but no luck... I completed quite a few sidequests, but now its just doesn't work.

I am using Patch 1.5.10 and Sky Reclamation Project 1.0.9.

I've uploaded my save file.
https://www.dropbox.com/s/wte1oief03qdol9/merin_quicksave.sav

Thanks for helping!

Thanks for uploading your savegame. I found the problem. There is a bug in the SRP.

Skip to the TL;DR part at the end of this post for a work-around if you're not interested in the nitty-gritty (which I'm writing in spite of that possibility, for future reference).

I made it possible in SRP v1.0.4 to have more than one active 'return item' task at a time. Unfortunately, I did not notice that GSC had done something quite lazy and unnecessary in task_objects.script which would give rise to the reported bug precisely if the player has more than one active 'return item' task at once.

The exact bug description is: If the player has at least two simultaneously active 'return item' tasks and one of them is completed/failed/cancelled, the dialogue option to complete the other(s) will be lost.

The technical reason for this is that GSC wrote the function task_objects.CRecoverItemTask:deactivate_task(task) to set squad.random_tasks[3] (the task table entry keeping track of the currently active 'return item' task, if any, assigned by the relevant squad to the player) to nil upon completion/failure/cancellation of such a task, not only for the squad that assigned the task (as it should be), but for every single squad in the Zone.

The reason they could get away with this is because in the vanilla game, only one 'return item' task (at a maximum) can be active at a time. But in the SRP, multiple squads can have a non-nil task table entry since the player can take multiple 'return item' tasks at once. Hence, when GSC's code takes effect upon completion/failure/cancellation of such a task, it incorrectly nullifies the task table entry also for the squads other than the one that assigned the task that was completed/failed/cancelled. The availability of the missing dialogue option depends on this entry being non-nil.

TL;DR: To work around this bug, open up gamedata\scripts\task_manager.script and replace lines 462 - 466 (inclusive) with the code below:

local task_squad = sim_board.get_sim_board().squads[inited_inspected_task.squad_id]
if inited_inspected_task.status == "selected" then
task_squad.random_tasks[3] = inited_inspected_task.entity_id
return
end
self.id_generator:remove(inited_inspected_task.entity_id)

Then load up your savegame and ask the target NPC for work. The lost dialogue option should reappear.

Thank you, the solution worked! :)