If I enable floating point exceptions for debugging purposes, they are triggered by McLachlan in the routine ML_BSSN_convertToADMBaseDtLapseShift_Body. The guilty line is
the involved values are (gdb) p rL $1 = 0 (gdb) p SpatialBetaDriverRadius $2 = 1000000000000
This only happens once per grid, apparently at the origin.
The results look fine otherwise, no NaNs or INFs propagated, but this is annoying when debugging other code, trying to find the first time a NaN is produced.
ET version is the Maxwell release.