There are verses missing from my text pane. For example, if I display Psalm 51 in English and put Hebrew in parallel, verse 1 in Hebrew with the first part of the title is missing.

You can be absolutely sure that there are no missing verses in any of our established Bible versions.

Ps 51 is one of a few Psalms where the so-called heading takes up 2 verses in Hebrew. Where the heading is a complete verse, vs 1 in Hebrew matches vs 0 in English. Where the heading is part of a verse, the Hebrew appears to have a missing verse 0 when the English is the search text, but when Hebrew is the search text, the English does display the heading.

There are many other places where users report that text is missing. The good news is the Accordance 11.2 will display these apparently missing verses in parallel panes. In the meantime the answer is always to make the text in which text seems to be missing, the search text. Then you can see if verses are really missing, or whether the other text actually has it combined with another verse, or is omitting it, or has renumbered it.