GM 18.1 regression: JP2 with 1-bit alpha no longer displayed properly

GeoloGIS
GeoloGIS Global Mapper UserTrusted User
We have JPEG2000 imagery stored as RGBA (RGB 3x8-bit + Alpha 1-bit) generated by Kakadu.

Under GM 17, the image was properly decoded, including the alpha transparency band (it is used to mask off-limits parts of rasters)
Under GM 18.1, the very same image no longer displays, as if the whole image was transparent.
(Imagery may still be revealed by disabling the alpha band, under Raster options / Band Setup / Ignore Build-in alpha)

500KB RGBA 8/8/8/1 sample file here: http://ge.tt/3NP1MWj2

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