Hmm, what is the original character data? I'm on a Mac, so I'm not sure I can reproduce your results. Using your dput() from above I got regular old "field" in all views:
Can you include a reprex with the code you're using to create the tibble?
# Characters f-i
pryr::bits('fi')
#> [1] "01100110 01101001"
# Manually entered latin small ligature fi
pryr::bits("fi")
#> [1] "11101111 10101100 10000001"
# from your top code chunk which case U+FB01
pryr::bits("field")
#> [1] "11101111 10101100 10000001 01100101 01101100 01100100"
# from your dput, which does not
pryr::bits("field")
#> [1] "01100110 01101001 01100101 01101100 01100100"
Created on 2019-01-04 by the reprex package (v0.2.1.9000)
Unless I’ve missed something, I don’t think this question involves R Markdown? The OP’s question appears to be about aspects of the RStudio IDE interface (viewer, environment pane).
I don't think this is an IDE issue, I think this has to do with the internal OCR library that the function pdf_text()uses, because I can reproduce on windows but get this completley different error on ubuntu (pdftools uses a different library for OCR on linux libpoppler-cpp-dev).