I have had a similar issue a few times (in 8 yrs) and blamed it on the filter needing cleaning (most likely, but you've checked that) -- possibly not visible junk, but just a film layer over the mesh, so scrub it well. I remember one time that my disposal got a piece of meat fat stuck under the blades. It must have wrapped itself around there because it took a while to figure out what was going on, but I mention it because I wondered if I could get some odor back into the DW even though the high loop would seem to prevent it.

One other thing you might want to try-- I used to use LemiShine from time to time, but what I'm using now is OxiClean DW detergent. Just half a cup cleans the dishes and the oxi power seems to really break down food particles and films -- so much so that I used a scoop of OxiClean (regular, not DW detergent) with hot water in my prep sink drain to help keep it clean when my prep sink disposal went out and before we were able to replace it (DH was out of town, of course). If you want to use the detergent you have, they make an additive that you just squirt into the bottom of the DW before running. Haven't had any issues lately.

Hope that helps.

I have a Bosch and, while I have some complaints, my dishes don't smell. There was a similar thread a few weeks ago, in Appliances I believe, and the source of the smell was discovered to be something other than the Bosch.

I would try changing your dishwasher detergent. I was using Electrosol which is recommended by Bosch and was getting a buildup of gunk. I switched to Cascade powder and the problem disappeared. It's worth a try.