Fullcalendar.js V5 Scheduler don't print vertical Lines if there is more than 1 page to print

This is my first question on stackoverflow, so if you think I do something wrong, be open to give me your Feedback. Thanks in advance.

I use the fullcalendar.js library, everything works fine except for printing.

I tried everything and I searched hours and hours in the Internet. So I'm pretty sure, that my question is not a duplicate, because no answers helped me with my problem so far.

If I print the calendar, it works perfect if I just have to print 1 page. If there is more than one page to print, the vertical Lines of the month are not visible.

Printing 1 Page Print preview with vertical lines

Printing more than 1 Page Print preview without vertical lines

I tried:

• every browser and it is still the same problem.
• every css options, also !important
• Html2canvas, Html2pdf
• everything in the print settings
• every other solution I found in the web

I'm using also the Bootstrap 4.0.0 libary and jquery 3.5.1

Did somebody had the same problem or an idea how to solve it?

Thank you all for your support.

Simba

this worked for me

@media print {
    .fc-timeline-slot-lane > div {
    position: absolute !important;
    border-left: 0.5px solid #ddd;
    margin-left: -0.5px;
    min-height: 100% !important;
}