Some sentences may cause "page text" selections to point on previous "source" object

Some sentences may cause "page text" selections to point on previous "source" object
It happened on different text
"page text" shows current selection, but in the "Source" and "Translation to ..." areas code points to the previous (-1 object). when editing, submits works and change goes to the previous "Source" (-1) as shown

All is happening after a sentence that cannot provide the "Source". The next selected sentence reveals the previous source an so on until the end

Any ideas?