The issue with settlement times is as sold as Investengine. Settlement time of T+2 is in place since December 2013. Guidance from London Stock Exchange states that “Rule 5011 continues to allow member firms to agree an alternative settlement due date of no more than 20 business days after trade date for on Exchange trades.”
Anything longer than that and the trade should be cancelled.
I’ve had emails from customer service giving me cut/paste blurb about how they will try blah, blah, blah all the while I was waiting on trades to settle so I could rebalance.
This is one of the major drawbacks with fractional shares vs. full shares only, regardless whether they are ETF’s or individual shares.