Please note that the indicators are not live, but instead are accurate to a certain point in the day when operational processes are performed that allow us to gain that data. The portfolio value, value difference in £ and TWR in % are not updated simultaneously and therefore there are times during the day when they might appear to "not add up". The value difference in £ and TWR are updated overnight, while the portfolio value is updated in the morning using the previous business day's end of trading share prices and then again at 2.30 pm using prices at the start of our trading window.
Our Development Team is currently working on synchronising these updates so that all three figures are refreshed simultaneously and are accurate in relationship to each other.
If you are new to TWR, please read this Community page which gives a more detailed explanation with easy to understand examples.