The first thing you can try is to increase the "Correlation window length" (at the expense of slower simulaton). It needs to be high enough to identify the delay.
I'd say that FIR filters introduce a delay equal to half their filter order. IIR filters can have different implementations. If you can see a filter order, that would be indicative.
If the delay block does not converge to a value, then it may be the case that your received signal is corrupted, so instead of computing BER, you can first troubleshoot by looking at some Constellation Diagrams.
