Non-Latin characters show as question marks when using rodbc/odbc/dbplyr with SQL-Server

I'm using dbplyr to get data from SQL-Server into R, but Chinese, Japanese and other non-Latin characters are appearing as "?". I'm using a windows machine.

I've read through the following threads:

• How does R handle Unicode / UTF-8?

• How to use Regex to strip punctuation without tainting UTF-8 or UTF-16 encoded text like chinese?

• Fetching UTF-8 text from MySQL in R returns “????”

These provide some useful ideas, but nothing has worked so far. I have tried:

• Setting encoding = 'UTF-8' within the dbConnect function. Characters still show as question-marks.

• Setting encoding = 'UTF-16' within the dbConnect function. R returns an error: # Error in iconv(x[current], from = enc, to = to, ...)

• Changing the global character encoding to UTF-8 with: Sys.setenv(LANG = "UTF-8") and options(encoding = "UTF-8")

• Checking if the characters display when plotting (which would indicate that they are being stored correctly). This wasn't the case.

I was able to get the characters to display correctly by using RJDBC, however this is not compatible with dbplyr, according to this GitHub issue.

Here is my session info:

> sessionInfo()
# R version 3.5.0 (2018-04-23)
# Platform: x86_64-w64-mingw32/x64 (64-bit)
# Running under: Windows >= 8 x64 (build 9200)

# Matrix products: default

# locale:
# [1] LC_COLLATE=English_United Kingdom.1252  LC_CTYPE=English_United Kingdom.1252    LC_MONETARY=English_United Kingdom.1252 LC_NUMERIC=C                           
# [5] LC_TIME=English_United Kingdom.1252

My code looks like this:

> con <- dbConnect(odbc(),
                   Driver   = "SQL Server",
                   Server   = "server name",
                   Database = "database name",
                   user     = "my username",
                   password = "my password",
                   encoding = "UTF-8")

odbc/dbplyr sure handles these character types on Windows, so what am I missing here?

Any help would be much appreciated!