How to set boxes for animated gnuplot - gnuplot

Question

I am trying to do an animated gif with contours from the dataset that looks like this:
"{/:Italic t} = 0 [yr]
-0.98 -0.98 0 0
-0.94 -0.98 0 0
-0.9 -0.98 0 0
-0.86 -0.98 0 0
-0.82 -0.98 0 0
-0.78 -0.98 0 0
...
"{/:Italic t} = 0.317 [yr]
-0.98 -0.98 0 -2.21572
-0.94 -0.98 0 -2.20023
-0.9 -0.98 0 -2.17084
-0.86 -0.98 0 -2.13024
-0.82 -0.98 0 -2.08149
...
gnuplot script is:
reset
set terminal gif animate delay 40
set contour
unset surface
set cntrparam levels incr -3,0.5,1
set output filename
set ylabel "{/:Italic z} [m]"
set xlabel "{/:Italic x} [m]"
set cblabel "{/:Italic x} [%]"
set cbrange [0:0.01]
set rmargin at screen 0.8
set palette defined ( 0 '#000090',\
1 '#000fff',\
2 '#0090ff',\
3 '#0fffee',\
4 '#90ff70',\
5 '#ffee00',\
6 '#ff7000',\
7 '#ee0000',\
8 '#7f0000')
set key center tmargin
set style textbox noborder
do for [i=0:9] {
set dgrid3d 50,50,1
set table $COUNTOUR
splot data u 1:2:4 index i
unset table
unset key
plot data index i with image title columnheader(1), $COUNTOUR w l lc rgb "white", '' u 1:2:3 every 50 w labels boxed tc rgb "white"
}
That produces:
I have 2 questions:
How to add invisible boxes for contours? I was trying to reimplement a thing that I've reused from the static example that works:
reset
set contour
unset surface
set cntrparam levels incr 0,1,4
set xrange [-0.5:0.5]
set yrange [-0.5:0.5]
set ylabel "{/:Italic z} [m]"
set xlabel "{/:Italic x} [m]"
set cblabel "({/:Italic P}) [Pa]"
set title 'P map + Tii contour'
set dgrid3d 100,100,1
set table $COUNTOUR
splot data u 1:2:4
unset table
unset key
if (!exists("filename")) filename='../VISUAL_TESTS/img/ShearTemplate.png'
set terminal png size 800,600;
set output filename;
set style textbox noborder
load 'inferno.pal'
plot data with image, data using 1:2:($5/10):($6/10) with vectors lc -1 filled, $COUNTOUR w l lc rgb "white", '' u 1:2:3 every 50 w labels boxed tc rgb "white"
Why all the sudden my dynamic title is not showing up after I've added contours? It comeletely ignores my with image title columnheader(1)