I downloaded and saw this also that the visually bar grew to about 25% then hid. What I think you are running into is the animation of the Progress control trying to make it appear to smoothly grow and not just jump to 100%.
What I did below is add a message at window open before the initial load so I could capture the bar only displaying about 25%. Then under the Reload button I added a message to the end of loading and you do see the bar grow to 100% slowly while the message is open, that’s the animation finishing.

If I remove the Manifest so the Progress is the old segmented style you see the bar grow to 100%.

In TakeProgress I checked for =100 and tried some things to get the displayed bar to jump to 100% but was not able, e.g. HIDE / UNHIDE, or reset RangeHigh … Ok this works to make the progress jump to filled. Set the RangeHigh to 1.
CSV.TakeProgress PROCEDURE(LONG pProgressPct,LONG pProgress,LONG pRows)!,DERIVED
CODE
Progress1 = pProgressPct
IF pProgressPct >= 100 THEN
?Progress1{PROP:RangeHigh}=1 !<=== Bar jumps to 100% filled
END
?ProgressText{PROP:Text} = pProgress & ' of ' & pRows
DISPLAY(?Progress1)
To assure you get to 100% in JSCSVParseClass.ParseColumns at the end of the LOOP you should add Self.TakeProgress(100, Recs, SELF.GetRowCount() )
You do have to remember to set RangeHigh back to 100 on the next load.
