Problem in RxODE (LOCF mode) / mrgsolve (LOCF mode), if 2 rows have the same time (often: OBS then DOSE), first row covariate value is taken! Workaround: identify these rows (group by ID and TIME) and apply a fill in the UP direction.
fillIOVOccColumns(table, columnNames, downDirectionFirst)
2-dimensional dataset
current table
the column names to fill
TRUE: first fill down then fill up (by ID & TIME). FALSE: First fill up (by ID & TIME), then fill down