Influential studies showed that 25-month-olds and neurotypical adults take an agent's false belief into account in their anticipatory looking patterns (Southgate et al. 2007 Psychol. Sci. 18, 587-592 (doi:10.1111/j.1467-9280.2007.01944.x);Senju et al. 2009 Science 325, 883-885 (doi: 10.1126/science.1176170)). These findings constitute central pillars of current accounts distinguishing between implicit and explicit Theory of Mind. In our first experiment, which initially included a replication as well as two manipulations, we failed to replicate the original finding in 2- to 3-year-olds (N = 48). Therefore, we ran a second experiment with the sole purpose of seeing whether the effect can be found in an independent, tightly controlled, sufficiently powered and preregistered replication study. This replication attempt failed again in a sample of 25-month-olds (N = 78), but was successful in a sample of adults (N = 115). In all samples, a surprisingly high number of participants did not correctly anticipate the agent's action during the familiarization phase. This led to massive exclusion rates when adhering to the criteria of the original studies and strongly limits the interpretability of findings from the test phase. We discuss both the reliability of our replication attempts as well as the replicability of non-verbal anticipatory looking paradigms of implicit false belief sensitivity, in general.