Hi Montana (A first name would be great, I think)
A warm welcome to this great forum of Märklin fans.
Here a crazy fan of Märklin digital HO with PC control (Rocrail)

K flexible track from Märklin is made of stainless steel rails, a flexible sleeper assembly with tie clips in which the rail is clipsed (slid inside).
A stamped (soft) steel is comb-shaped with bent extremities to provide the studs for central current pick-up. This "comb" is alternately on one side or the other to allow any bending without changing the total length of the flexible rail assembly (up to a point).
On some locations there are no tie clips ON PURPOSE to insert various optional components like the 7500 geound connector

but also catenary masts (7509; 7510, 7512) and K-Track signals like 7237, 7238, 7239, 7240, 7242

To be fair, I am not a big fan of K track because it is not finely detailled, its contact system does not cohabit well with the glue used when ballasting (many contact issues) and its switches are assembled like a jalopy. Far better is the C Track which becomes really prototype-like if you take the pain to paint the rails sides with a rust color using a marker or a fine brush and acrylic paint.
Here is a glimpse of my digital HO layout where you may see both K flexible track and all the rest is C Track


Cheers
Jean

You can also cut K track and section in as needed using the rail joiners. Not an issue with all K track, but say you want to use C track, and K track on a bridge for correct profile height, be careful. The C and K standard striaght sections are not of equal length.

The flexible K-track is made like this on purpose.
Aparently they (Märklin & Cie GMBH) found it OK to re-use the plastic sleeper-part of the 180cm long standard straight.
It´s a little annoying, but not an issue for its functioning.

The track-piece has another interesting "feature" that you should absolutly be aware of; Depending on the version (I know at least two different ones) you can find "grips" for the rails into the plastic sleepers at each end of the piece. Except ONE of the rails in ONE of the ends; This is important to know about when you want to flex the track and needs to shorten one of the rails; The plastic-sleepers (and thus the pukos!) flex differently left and right; To ONE side it will compact the sleepers and you will need to cut one of the rails (This "correct" method). To the OTHER side it will strech the sleepers, and you will need to add a piece of rail on one of the sides (the "wrong" method).
Anyway; there should be a small paper-instruction included in each box explaining the situation.

Apart from that;

I highly doubt that is the reason, as all these pieces fits perfectly anywhwere on any other track piece.
It doesnt matter if there are tie clips or not.

Also;

Older versions of the track had copper tounges for connecting the mittelleiter between each piece, but today they use another material (phosphorized copper¿?), which doesnt oxidise any more than any C-track piece.
Anyhow... My own layout, which has a LOT of traditionally ballasted K-track (even with copper-connectors) works perfectly still.
Some of my oldest K-track has been ballasted 2 times before on previous layouts, washed out and re-used over the last 30 years.
You could also use BenP´s suggestion of using Merkur bedding which should solve any glue-problems.

A bit off the subject but I recently saw a display of k-track which included the rail joiners for the outside tracks - not unlike that which is used in two track ho. Bur what no one at the time, most of us are m or c track, could explain was how the center rail was connected between sections.

The big advantage for K track is you can cut any piece of track and attached the rail piece (7595).

This allows near unlimited curve/track geometry for your layout. You can also use 3rd party turnouts (peco/WeichenWalter) to allow even more flexibility.