although I can imagine a cut in liquidity would cause orders not to be filled, I don't think it would explain :-
1. Why cannot access myig and then the platform
2. Why the price feed stopped working through the API
3. Why sometimes myig worked but could not switch accounts
My guess, for what it is worth, is there is a significant increase in users around the US open and for some reason now the IG systems cannot cope, maybe there has been a sudden increase, or a significant build up since the beginning the of year.