Header content removed LO5-4.2.1

Running LO-5.4.1 on Slackware-14.2. I have a letterhead template that has
worked for me for several years in the first page header of letters.
Yesterday (running LO-5.4.0) the header content disappeared suddenly. I
still cannot get it back. Needing to get out a letter I inserted a
letterhead .pdf file in the header and was able to print that to file before
the image was removed.

   I'm open to suggestions for diagnosing the cause of this problem.

Rich

hello.
use the version that its third digit is 6.
the version 5.3.6.1 is available in the last day of august and 5.3.7
is near to come.
the versions that there third digit is 0, 1 etc are not stable
unfortunately very stable and may have many bugs!
hope that help, God bless you!