cathyMc: I'm still having these problems a year later, and though I LOVE the game, it's frustrating to see my work go to nothing...
I'm also getting a "reverse" glitch now - a builder is hammering at a building, then suddenly a box of fish (for ex.) appears in his arms and he walks off! But sometimes walks that box into wilderness and drops it. Any response very welcome!
Look at the inventory tab rather than what is in their arms. What is in their arms can change based on their current task but it does not mean that the item is gone (or appeared out of nowhere), it just means that they now have a new primary task.
I just wached a forester with wood in her arms get distracted to plant a tree, then walked past a storage area with space to cut down another tree, but couldn't hold any more so left a pile there, walked home, walked to the market to get clothing, walked home again, planted a few more trees, cut down another tree and left a pile, then delivered the wood she was carrying to the ground next to a full storage area. It only looked like she had wood briefly two or three times but it was in her inventory the whole time.
Similarly, individuals in the game change jobs all the time (I think mostly to try to get everyone, including laborers, to live as close as possible to where they are working) and they will often head off to the new job with whatever they have in their inventory. Or, like with the forester, if interruped they will forget to go back to whatever they were doing and only after attemting to do something else will rediscover that they need to drop off an item first. I'm guessing this is also part of why further away resources can take forever for laborers to pick up even when they are visiting the area with the resources.
I think there are two basic things that can be done to limit this inefficiency (as others have said): try to not have laborers do anything too far away from housing and try to have storage areas fairly close to where they are gathering resources. The bad part about having storage areas too far away is that other laborers will go all the way there just to pick up something to carry to a building site while the ones gathering the resources will often go back with empty hands, so having them somewhat closer than the resources being gathered might be best. I at least try to put a small storage area at the end of every road when gathering nearby resources.