AdvStringGrid - Checkboxes don't show up

So this code worked for over a year now:

  while IsFound do begin
    if DS_E.RecordCount>0 then
        AdvSG_Rueckscheine.Cells[3,AdvSG_Rueckscheine.RowCount-1]:=FormatDateTime('DD.MM.YYYY', DS_E['datum_einlieferung']);
        AdvSG_Rueckscheine.AddCheckBox(0, AdvSG_Rueckscheine.RowCount-1, true, false);
      AdvSG_Rueckscheine.AddCheckBox(0, AdvSG_Rueckscheine.RowCount-1, false, false);
    IsFound := FindNext(SR) = 0;

But since I compiled with a VCL UI Pack version 10.3 or higher the checkboxes don't show up anymore.
Why is this?
What do I have to change for the updated StringGrid?

Oh, and I don't have any fixed columns. Just like the 18 months before.

What operating system do you use?
Did you test it on multiple machines?

It is always Windows 10.
I tested on different machines, my own and two of my customers. All of them are Windows 10 machines. All are 64bit OS and the program is also on 64bit.

What freaks me out is, I didn't touch this area of the code for months and just compiled new for having changed code on other forms.
I tried the DoubleBuffering that solved a problem on another issue in this forum some time ago. But that didn't help either.

I will try to test on a freshly inserted StringGrid.

We're investigating a potential 64bit related issue and will report back on this as soon as possible.

Can you test if adding 


at the top in AdvXPVS.pas solves this?

It does!

Now it shows a checkbox in the fixed row, too, which I think it didn't before. 
But that is not important to me - at least now - since

AdvSG_Rueckscheine.RemoveCheckBox(0, 0); does the trick for this.

Thanks for your help once again!

We had the same problem after the update, but this solved it.