There seems to be some problem with OSAT that doesn't return the same size of data that was used for input:

library("OSAT")
data(survey, package = "MASS")
VoI <- c("Sex", "Smoke", "Age")
n_batch <- 3
iterations <- 10
gs <- setup.sample(survey, optimal = VoI)
gc <- setup.container(IlluminaBeadChip96Plate, n = n_batch, batch = 'plates')
gSetup <- create.optimized.setup(sample = gs, container = gc, nSim = iterations)
#> Warning in create.optimized.setup(sample = gs, container = gc, nSim =
#> iterations): Using default optimization method: optimal.shuffle
OSAT_index <- get.experiment.setup(gSetup)
dim(survey)
#> [1] 237  12
dim(OSAT_index)
#> [1] 236  19

^{Created on 2021-04-14 by the [reprex package](https://reprex.tidyverse.org) (v2.0.0)}

Inspecting the data it seems to be the sample 137 which on the first column has an NA. But couldn't find a confirmation this is the reason.