Can not confirm on Windows 10 Pro 64-bit en-US with
Version: 5.2.1.2 (x64)
Build ID: 31dd62db80d4e60af04904455ec9c9219178d620
CPU Threads: 8; OS Version: Windows 6.19; UI Render: default; 
Locale: en-US (en_US); Calc: group

Please provide a test ODG that is failing filter saveas to MSOffice 97-2003 PPT format and complete steps to reproduce.

Also, a four year old isuue like bug 51179 does not provide test case nor is it likely relevant to your new issue.

Confirmed on Ubuntu 14.04.5 and Ubuntu 16.04.1 on x86-64, using both LibreOffice 5.2.0.4 and 5.2.1.2 installed from the LibreOffice PPA.
Multiple computers with different versions listed above, same result. The issue is reproduced by opening an ODP and trying to save it as PPT (nor PPTX).
The message is exactly as reported in the first comment of 51179.

No repro with v5.2.0.4 (TDF build) / Ubuntu 16.04.
Does it happen with any ODP for you?

As Stuart wrote, the error message is too general to imply any kind of connection with bug 51179.

I can try purge and re-install of packages to make sure it's not a configuration problem. Given that I tested on multiple machines, this is not very likely.

Another common property of all the machines is setup with non-default locale. Specifically, LANG is set to en_US.UTF-8 and there is a secondary Hebrew language installed after the primary English. Also, the regional data (currency, date/time etc) is set to Hebrew format, e.g., LC_TIME = he_IL.UTF_8. Can anyone confirm in this setup?

UPDATE: I downloaded a random ODP from the net (http://www.openoffice.org/marketing/ooocon2008/programme/friday_1484.odp), tried to save it as PPT using LibreOffice 5.2.1.2 on both Ubuntu 16.04.1 and 14.04.5 - and IT WORKED (with the exception of a few missing images on slides). 
This is much better than where I got to before.

So, I think this has something to do with the locale. I can load ODP presentations that I created on my machines (see locale setting in above comments) but I cannot save them as PPT.
Given the sensitivity (private and commercial) of the material in the presentations, I cannot share them as test material for others to confirm. Is there a test machine where someone can install a locale setting like mine with LibreOffice 5.2.0.4 or 5.2.1.2 and try to confirm this issue?

Why not create a simple test document that shows the problem?

Set to NEEDINFO.
Change back to UNCONFIRMED after you have provided the document.

Dear Bug Submitter,

Please read this message in its entirety before proceeding.

Your bug report is being closed as INSUFFICIENTDATA due to inactivity and
a lack of information which is needed in order to accurately
reproduce and confirm the problem. We encourage you to retest
your bug against the latest release. If the issue is still
present in the latest stable release, we need the following
information (please ignore any that you've already provided):

a) Provide details of your system including your operating
   system and the latest version of LibreOffice that you have
   confirmed the bug to be present

b) Provide easy to reproduce steps – the simpler the better

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Once all of this is done, please set the bug back to UNCONFIRMED
and we will attempt to reproduce the issue. Please do not:

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b) update the version field in the bug or any of the other details
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MassPing-NeedInfo-20170502