Your expected an arc and see (get) a straight line, I assume.
Tell us a a whole lot more about what machine you have and your environment.
tinyG FW version – parameter $fb.? build 440.14 is most up to date
How do your interface with tinyG? (Cool Term, ChiliPeppr, Universal Gcode Sender)?
What OS on you controlling PC?
tgFX does not modify Gcode before sending, and tinyG does what it is told to do, get an arc, draw an arc.
tgFX is no longer supported and does not work well with up-to-date tinyG FW.
A quick way to provide information would be to post your parameter file.
See