I've never had a problem with M4 (or V4) and all his morphs. I use Poser 10 and Windows 10.

What I did:

-install Daz Studio.

-download and install M4 and all his morphs into Daz studio using their downloader.

-add "My Daz Library" as a runtime in my Poser Library.

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I load base figures accessing the "My Daz Library" as a runtime in Poser

I add morphs

I then turn off the lights and save the base figure as a poser file

I have a bunch of V4/M4 figures loaded with various morph combinations (Most V4 characters require only V4++, some require A4 or Elite and A4 etc.)

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When I want to build a character I import the saved figure and go to work on them

I then save the character as a poser file to be imported as I need it

I import a naked character into the work space, dress them and save them as a new file to be imported into a scene

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My Daz Library is located (for me) Local Disk >> Users >> Public >> Public Documents

I don't recall if I had to tell Daz Studio to place the folder there or not (its been a couple of years at least)

All of my Poser content that I install is stored in separate runtimes. I have one for poses, one for lights and materials, one for V4 contemporary clothing, one for hair etc. I did this as a way to organize my stuff so as not to loose it. (I also keep an Excel spread sheet with each item, it's location and notes I make on the utility of some items like clothing or hair)

These runtimes are located in a folder in My Documents

I never use Poser to install my content, I do it all by hand, this allows for greater control over the organization of my runtimes. I always put material files in a subfolder within the item they are for.

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Using DSON is tricky You need to install the original files into the Daz library (via Daz studio) You then need to install the Poser Companion files for the Daz files in poser in a runtime you can access. I have not attempted to use Genesis as I have a significant investment in V4/M4 characters and clothing but I have a few Daz hair pieces that needed DSON

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Sorry about the separation lines, but this editor runs all my individual lines of text together into paragraphs which seem harder to read. So I have to double space everything which looks messy. Hope this is helpful in some way.