TimeAxis not working in perspective 4.0.0

[sambhav8]

Migrated my code from 2.X to 4.0.0 i have chart for 3 values ( bid ask mid updating every 1 sec) . but when having graph update every time 13Error: attribute transform: Expected number, "translate(NaN, 0)". error please see attached python script and html . as per migration I had changed from date time to str type for table schema definition Please see attach file
t.py
t.html