Here is a minimal example:

> getParseData(parse(text = 'γ <- α + β ', keep.source = TRUE))
   line1 col1 line2 col2 id parent       token terminal text
11     1    0     1    7 11      0        expr    FALSE     
1      1    0     1    0  1      3      SYMBOL     TRUE    γ
3      1    0     1    0  3     11        expr    FALSE     
2      1    2     1    3  2     11 LEFT_ASSIGN     TRUE   <-
10     1    4     1    7 10     11        expr    FALSE     
4      1    4     1    4  4      6      SYMBOL     TRUE    α
6      1    4     1    4  6     10        expr    FALSE     
5      1    6     1    6  5     10         '+'     TRUE    +
7      1    7     1    7  7      9      SYMBOL     TRUE    β
9      1    7     1    7  9     10        expr    FALSE     

You can see that γ's col1 is 0 and col2 is also 0. <- should be from column 3 to 4 instead of 2 to 3. α should be from 6 to 6 instead of 4 to 4, etc.

My session info:

> sessionInfo()
R version 3.3.3 (2017-03-06)
Platform: x86_64-apple-darwin13.4.0 (64-bit)
Running under: macOS Sierra 10.12.4

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base