I've had problems a few times with gate readers and pre-pay. I've
exited at Limehouse DLR station and the reader said "closed" on it.
Absoutely nothing I could do but have an unresolved journey. I've
entered Kings Cross late at night during development works and all the
gates were set to exit mode and had an unresolved jounrey at my exit
because I had no entry! Lastly Southwark station is a nightmare if
using it as a walk through from Waterloo East to the main exit as it
doesn't let you through the gates at the other end and gives you an
unresolved journey. Admitely I haven't done the Southwark jounrey for
other a year so does may have been resolved by now....

wrote:
asdf wrote:
Since then, I've always waited for the gates to close before touching
my card on the reader, and I haven't had a problem since.

Thats perhaps the best advice. Well, you don't have to wait til the
gates CLOSE, but its a good idea to make sure the person in front is
already walking through them before your Oyster goes near the
validator!

Less haste more speed as they say.