The built-in Windows folder compression reduces free disk space instead of increasing it

Question

A few months ago I did not have enough free space on my Windows 7 drive so I went ahead and compressed some big folders with the built in compression tool in Windows which is accessed from the Properties dialog of folders. The free space of my drive was successfully increased back from what I saw after completing this operation.

This was my observation about a month ago but now whenever I try to compress a folder in my Windows drive, the tool actually reduces the drive's free space instead of increasing it.

Question

How can enabling compression on a folder with the built in Windows functionality take away from the free space on a hard drive's disk partition?
What causes this and why is it taking free space now?
It worked one way in the past for some folders and now another way with other folders.

Further Information

The folders I enabled compression for were individual folders inside the ~\ProgramData and ~\Program Files folders of my C drive. A few months ago the compression on each new folder I compressed increased my drive's free space but now it's reducing it when I compress.

For example I have a folder called "\ActiveMARK" inside the "\ProgramData" folder which is 600 MB. When I compress it my disk space is reduced by 200 MB. If I disable again the compression I gain the 200 MB back. Also, I have a feeling that this behavior started to happen because I enabled System Restore on my C drive?

@JakeGould I can see in real-time how much space I have before and after with Directory Opus program. Also I'm not compressing already compressed multimedia, just programs inside the "program files" folder. I don't always expect the free space to be increased but it always decreases no matter what I try to compress. — Stavros Skamagkis, Jul 01 '18 at 23:50
@JakeGould I don't understand why you guys flagged my question as too broad? My problem is very specific, it has to do with the file compression tool of Windows. What should I add to make it more specific? — Stavros Skamagkis, Jul 02 '18 at 14:12
As to the reasons this question is broad. You don't indicate which folder you enabled compression on originally. Depending on that information, compression might already be on, you might be disabling compression instead of enabling it. — Ramhound, Jul 03 '18 at 14:02
@Ramhound I enabled compression on individual folders inside the ProgramData and Program Files folders of my C drive. A few months ago the compression on each new folder I compressed increased my drive's space but now it's reducing it. — Stavros Skamagkis, Jul 03 '18 at 17:57
I still think there are too many possible reasons for the increase, and people will just be guessing, but I'll vote to reopen because a number of people's comments indicate that they think the question is answerable. — fixer1234, Jul 04 '18 at 04:50
you may get better savings by reducing pagefile and hibernate file size, or move the pagefile to another drive and turn hibernating off. Better use a disk analyzer like treesize to see which file/folder takes a lot of space and move or delete them. If you have some other volumes try resizing them and increase the Windows drive, or move some folders there and create a junction point back to C — phuclv, Jul 06 '18 at 17:20
that said, Lossless data compression algorithms cannot guarantee compression for all input data sets. In other words, for any lossless data compression algorithm, there will be an input data set that does not get smaller when processed by the algorithm, and for any lossless data compression algorithm that makes at least one file smaller, there will be at least one file that it makes larger — phuclv, Jul 06 '18 at 17:23
is this a duplicate of ( https://superuser.com/questions/605398/ ) ? — Yorik, Jul 06 '18 at 17:24
Possible Duplicate: https://superuser.com/questions/464315/why-is-a-7zipped-file-larger-than-the-raw-file .... I know this has to do with 7Zip but the answer seems to give a reason this would something compressed to become larger so I think it's a duplicate of the accepted answer there giving a reason why this is occurring now—this touches on that lossless Wiki that @phuclv linked to as well I think. — Vomit IT - Chunky Mess Style, Jul 17 '18 at 23:35
I'm just seeing the same thing, I'm compressing some folders and the free space instead of increasing is decreasing, I used to have 930GB free space, now I've got 700GB - I just hope it's temporary data that Windows creates and will be removed when it's finished. — Mike, Oct 09 '19 at 16:03

The built-in Windows folder compression reduces free disk space instead of increasing it

Further Information

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