flextable throws error when saving a table to docx with equations in a column

Example

I have this equation column in my table that when I convert to flextable and save to a docx file, it throws an error. However, the same table is successfully saved to html. But unfortunately, when I try to copy the contents of the saved table from the html file, this equation column is not selected as it seems that it is rendered as an image.
In the following example, I am showing only that 1 column that is the source of the error. IS there any possibility to save it directly to a docx file? Thank you.

library(flextable)

paramz_namez <- c("T", "A_i", "b", "v_0", "\\delta", "s_0", "k", "A_+", "A_-", "\\lambda", "a_{BL}", "p_{BL}", "M", "\\tau_p", "\\tau_m", "\\sigma_n", "\\sigma_m", "\\Delta{T}", "G_std", "\\Delta{T}_{p0}", "\\Delta{T}_{p1}", "H_std")

ftt <- flextable(data.frame(Parameter = paramz_namez))

ftt <- compose(
  x = ftt, j = "Parameter",
  value = as_paragraph(as_equation(Parameter, width = 2, height = .5)))


flextable::save_as_docx(ftt, path = "params.docx")

Error in read_xml.raw(charToRaw(enc2utf8(x)), "UTF-8", ..., as_html = as_html,  : 
  error parsing attribute name [68]