[VegGirl7]

Could it be that you're using table salt with iodine rather than canning/pickling salt? Table salt
often contains additives for free flowing and other nonsense and this might be interfering with it dissolving.

   I was planning on doing pickled onions and asked the OH to buy plenty of salt next time he was shopping...  I now have a large bag of table salt!!

Didn't realise I needed different salt    - am I going to have to get some cooking salt to make my brine?   

[Aunt Sally]

Table salt will do fine.  !