Just tried to share participants in IE and it started to hide the list on me as well.
Also, I seem to have high resource use on this hosting account, higher than I would expect this time of day.
And, not sure if this makes a diff, but there are >1000 participants.

Just reviewed list again in IE, and the import of the attributes appears to have failed, they are not on the list.

Anyone any thoughts? I would love to move to the new version but can't if people can't see the participant list.

Well, then. This was somehow related to the import file or the attribute options. I messed around with both for a while. Had deleted all participants already and still the panel buttons were not visible. When I deleted about half the atributes suddently the buttons showed back up. Two possible things:
one attribute had a "&" in the name
one imported attribute had commas in it, so it spread it over many columns, possibly more than there were in the list?

Not looking into any further because problem is solved at my instance, but a bug likely persists.

The .csv export file could be useful to try to reproduce the error.

ttenberg, or it is just a memory problem. Did you try raising your memory_limit variable in your PHP configuration?

re. Memory: I have LimeSurvey installed in a hosted environment, under Installatron. I don't have access to the php memory settings. The whole reason I am trying to import this into a new instance is because the old one has not been updating for months, possibly in part due to memory. Initially it would just break if I did a plain upgrade under installatron; could not load LimeSurvey after upgrade. So, I did a clean install and tried to restore the data into that. It tried to run and then stalled out. Saw somewhere online that it would likely be a memory issue. Asked our host to do something about it, but he wanted specifics I don't know (like how much memory I would need) so I gave up and decided to do a new instance instead.
So, you may be onto something in that this could be memory related. If it is, though, then a check before starting, with a meaningful error, would be preferrable over the crashes. I actually get it, though, that may not be easy to do.
FYI: the old install has over 1000 surveys in it, which leads to a lot of tables. Figured it might be relevant because I have had problems dealing with that in things like phpMyAdmin to back up data.

RE .csv file
I can't send the original file, both because I think it got lost in all my troubleshooting and because it contains >1100 names and email addresses I would not be allowed to release.
I went back into the file and stripped out all but two participant lines. I kept two where the extra commas actually push the data lines past the last header line. I have uploaded it.
I tried re-importing this one, and it just seems to hang after I press continue on the mapping/import screen. This is not what happened originally. This reminds me, though: I think on the original import I first imported just names and emails because the initial .csv file didn't include the attributes. I then did a re-import to map the attributes. I think it may have been after that that I lost the buttons on the participant screen.

Alternative to not allowing commas the export could do string delimiters... as of Version 2.05+ Build 141210 it doesn't.

Memory limitation errors are beyond our control as PHP does not properly catch it.

So, basically you cannot help us get more information because you did not really install anything yourself and it is running on some environment you cannot control.
I will close the issue because this is end of the line.

If you need more help please consider to contact one of the LimeSurvey Partners http://www.limesurvey.com , they may be able to help you with your specific problem for a fee.