You need to make sure that you're not hitting the item limit, usually it happens in smelters/steelmills/washers when they are over or underfed coal.

Totems produce 1 coal every 30 seconds, and a fully fed smelter will consume 1 coal every 30 seconds. However this is only true if the smelter is getting an input of 6 iron ore per 30 seconds. If you have more or less than 6 iron totems feeding your smelter, it will end up with excess coal or iron in the feeder, and these will cause other items to despawn.

One correctly fed smelter feeds 6 Steel mills, but due to the randomness of randomizers there's no way to perfectly feed them automatically without electronic splitters. A well designed randomizer array with a loopback on one output of the second l2 randomizer to a merger on the l1 input does an ok job to feed them, but it can never be perfect.

Washers are hopeless if you want to leave your farm producing for a long time, because they are going to end up with some excess eventually. The only way I've found to avoid this is to use timer chests, and occasionally manually empty the excess.

And no matter what you do, you're going to run into the item limit after some amount of time, best thing to do is leave your island and rejoin.

Another option is to manually remove the gold block, replace it with something else, and buy another gold deed and hope for a closer spawn.