It is very frustrating. If they offer it for some markets, why not offer it for all. IG are rated as one of the best UK Share Dealers, but this seems like a very basic functionality that is missing!. Please get this sorted and extend to all markets.
I'm also having the same issue. On some shares (e.g. ITM Power) I have the option to place a "Stop Order". This is what I would use to place my 'stop loss'. However on another share (PHE) I don't have that order type, so can't set a stop loss. See attached snips.