At the crossroads of English as a lingua franca (ELF) research and interpreting studies, it is paramount to examine why interpreters are at odds with ELF communication in general and with the effects of the output of the growing number of non-native English conference speakers on their work in particular. On the basis of a small-scale case study, the stumbling blocks resulting from non-native English input are examined. The findings point toward what may be a major impediment: activation and retrieval constraints can result from ELF speakers’ restricted power of expression and have an adverse effect on the interpreter’s inferential processing and target text rendering. In the discussion, it is argued that a key problem for devising compensatory (strategic or didactic) measures may lie in the unpredictable and open-ended nature of the means of expression creatively constructed by ELF speakers, which makes it extremely difficult for interpreters to build up a stock of resources that will match the ongoing input items, allowing them to function as activating cues.