  Understanding if and when the accretion disc extends down to the innermost
stable circular orbit (ISCO) is important since it is the fundamental
assumption behind measuring black hole spin. Here, we examine the 2013 and 2018
NuSTAR and Swift data (0.5 - 50 keV) of the narrow-line Seyfert 1 galaxy, WKK
4438. The X-ray emission can be fitted well with models depicting a corona and
blurred reflection originating from a disc around a low spin (a* ~ 0) black
hole. However, such models result in unconventional values for some of the
parameters (e.g. inverted emissivity profile and high coronal height).
Alternatively, equally good fits can be achieved if the disc is truncated at
~10 rg and the black hole is spinning at the Thorne limit (a* = 0.998). In
these cases, the model parameters are consistent with the interpretation that
the corona is centrally located close to the black hole and illuminating the
disc at a larger distance.
