All, first of all: great to see everybody helping eachother here!
There are some bugs in bunq2ifttt at the moment with caching of data in the application. During normal use and during initial setup this does not cause any problems, however it does cause some problems when you use the webinterface later on, e.g. when trying to setup OAuth again. I am planning to fix these bugs, which unfortunately requires a bit of work.
Due to the changes that bunq recently made where with OAuth only a selection of accounts will be authorized, it is not possible to add a new account to an existing OAuth authorized connection. This will mean more frequent reauthorization is required, so even more important for me to fix this!