Hmm. File upload hasn't worked. What do do?

Assuming that this might be related to the target-language attribute in your file. You can use my email address and send the sample file directly to me.

Thanks!  Done.

PS. I'm also not getting the XLIFF "Notes" imported as comments into LPU1.  I have found the trouble ticket about that in this forum, and its solution, but I need some help understanding and implementing it:
community.sdl.com/.../74713

The first problem is related to the source-language attribute in the <file> element. You are using en_devel which is not a valid language attribute, but this prevents the alignment. Changing it into en will fix this issue.

The second problem with the comment is related to a bug that now exists for more than 15 years in the underlying Microsoft MSXML parser and is related to using the xmlns attribute in the <xliff> element.

I would recommend copying the standard XLIFF rule into the Custom rules or directly into the project and adapt it. The Meta Data entry parent::*/descendant::note must be changed into parent::*/descendant::pdns:note. This will fix the issue. See https://docs.sdl.com/785448/403814/sdl-passolo-help/working-with-xml-namespaces for more details.

Many thanks, as ever, Mr. Herrmann!
I will try out your suggestions and verify the answer ASAP. 

I suspected and tried the source-language "en" myself yesterday, but only in LPU2. This time I will try from scratch (LPU1, LPU2).

Am I correct in saying that the target-language name is less critical, and not used at all if each alignment file contains only one target language?
If I am NOT correct, where can I find a list of the language abbreviations that Passolo permits? Note that we have 2 variants of Chinese, and there seem be variant naming schemes, e.g. zh-tw, zh-hant etc.

I confirm that changing the source language to from "en_devel" to "en" fixes the alignment problem.  The target language in the dialog window is always displayed as English (i.e. the source), but in fact the translations FROM English are imported.

I will have to get back to you on the Notes/Comments xmlns change. I have forwarded your fix to the SW-developers on the assumption that they will know where to edit.

Thanks again.

If you'll permit me another quick XLIFF import question here:
The main stringlist window is displaying apostrophes, double quotes etc. in "&" syntax, e.g. Can&apos;t instead of   Can't  (as in the XLF file).   
Nevertheless, in the properties widget, in menu:View>Show Resource, AND even in the stringlist window when you select a cell, the display reverts to Can't .

Now the "&" syntax makes languages like English and French hard to read.  Is there any way to suppress the "&" syntax display generally in the stringlist window?

This is by design. Conversion into entities happen, when the Microsoft MSXML component is reading the file. In the list Passolo always display the raw data while it converts it back into for the editing window.  

Thanks. OK, noted, but that design decision makes it very difficult to skim through translations quickly in the string-list window. You have to click in each cell to make it readable.  it would be nice if it were the other way round, or optional (e.g. a toggle-able display).
French, English, and any strings containing single or double quotes are particularly badly affected.

Maybe one for the backlog? ;-)