Predict only predicts outcome for one of four samples

I am unable to reproduce the error here. I receive the following results:

suppressMessages(library(mixOmics))
data(breast.TCGA)

train.samples <- c(1:6, 77:83)
X.train <- breast.TCGA$data.train$mirna[train.samples, ]
Y.train <- as.vector(breast.TCGA$data.train$subtype[train.samples])

test.samples <- c(7,8, 84, 85)
X.test <- breast.TCGA$data.train$mirna[test.samples, ]
Y.test <- as.vector(breast.TCGA$data.train$subtype[test.samples])

MyResult.splsda.final <- splsda(X.train, Y.train,
                                keepX = c(100,100)) # tried a range of values

# USING TRAINING DATA
pred=predict(MyResult.splsda.final, X.train) 
Prediction <- pred$class$mahalanobis.dist[, 1]
Prediction 
#>    A0FJ    A13E    A0G0    A0SX    A143    A0DA    A0B0    A18S    A0CS    A0EI 
#> "Basal" "Basal" "Basal" "Basal" "Basal" "Basal"  "LumA"  "LumA"  "LumA"  "LumA" 
#>    A0IO    A0T6    A1AU 
#>  "LumA"  "LumA"  "LumA"

# USING TESTING DATA
pred=predict(MyResult.splsda.final, X.test) 
Prediction <- pred$class$mahalanobis.dist[, 1]
Prediction
#>    A0B3    A0I2    A07Z    A0XS 
#>  "LumA" "Basal"  "LumA"  "LumA"

Created on 2022-09-20 with reprex v2.0.2

Session info
sessioninfo::session_info()
#> ─ Session info ───────────────────────────────────────────────────────────────
#>  setting  value
#>  version  R version 4.2.1 (2022-06-23 ucrt)
#>  os       Windows 10 x64 (build 19044)
#>  system   x86_64, mingw32
#>  ui       RTerm
#>  language (EN)
#>  collate  English_United States.utf8
#>  ctype    English_United States.utf8
#>  tz       Australia/Sydney
#>  date     2022-09-20
#>  pandoc   2.18 @ D:/Programs/Work Programs/RStudio/bin/quarto/bin/tools/ (via rmarkdown)
#> 
#> ─ Packages ───────────────────────────────────────────────────────────────────
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#>  BiocParallel   1.30.3   2022-06-07 [1] Bioconductor
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#>  knitr          1.40     2022-08-24 [1] CRAN (R 4.2.1)
#>  lattice      * 0.20-45  2021-09-22 [1] CRAN (R 4.2.1)
#>  lifecycle      1.0.1    2021-09-24 [1] CRAN (R 4.2.1)
#>  magrittr       2.0.3    2022-03-30 [1] CRAN (R 4.2.1)
#>  MASS         * 7.3-58.1 2022-08-03 [1] CRAN (R 4.2.1)
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#>  matrixStats    0.62.0   2022-04-19 [1] CRAN (R 4.2.1)
#>  mixOmics     * 6.20.0   2022-04-26 [1] Bioconductor (R 4.2.0)
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#>  purrr          0.3.4    2020-04-17 [1] CRAN (R 4.2.1)
#>  R.cache        0.16.0   2022-07-21 [1] CRAN (R 4.2.1)
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#>  reshape2       1.4.4    2020-04-09 [1] CRAN (R 4.2.1)
#>  rlang          1.0.4    2022-07-12 [1] CRAN (R 4.2.1)
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#>  scales         1.2.1    2022-08-20 [1] CRAN (R 4.2.1)
#>  sessioninfo    1.2.2    2021-12-06 [1] CRAN (R 4.2.1)
#>  stringi        1.7.8    2022-07-11 [1] CRAN (R 4.2.1)
#>  stringr        1.4.1    2022-08-20 [1] CRAN (R 4.2.1)
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#>  tidyr          1.2.0    2022-02-01 [1] CRAN (R 4.2.1)
#>  tidyselect     1.1.2    2022-02-21 [1] CRAN (R 4.2.1)
#>  utf8           1.2.2    2021-07-24 [1] CRAN (R 4.2.1)
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#> 
#>  [1] D:/Programs/Work Programs/R-4.2.1/library
#> 
#> ──────────────────────────────────────────────────────────────────────────────

To help I’d first need a reproducible example (as described here and in the banner). From there, we can potentially discuss me accessing your data and scripts to evaluate them for issues. Feel free to directly message me via the forum