Hello all, The team have been working for some time to address an issue with \bool_if:n(TF), namely that under some circumstances lazy evaluation can lead to serious bugs. This is a consequence of working expandably and cannot be avoided with lazy evaluation. In the latest CTAN update, \bool_if:n(TF) has been made *greedy*: \bool_lazy_... functions are available for lazy evaluation. (The latter have a different input syntax which does not suffer from the issue that affects \bool_if:n(TF).) Any code which still assumes lazy evaluation for \bool_if:n(TF) will therefore need adjustment. Regards, Joseph