Asus Maximus Z790 Hero Been running 2x16GB ok
Just bought another same kit and system would not show XMP tweaked profile for 4 sticks but will for 2 sticks.
IT will boot in auto mode 4x16GB but only in 2400mhz so its but just not at designed speed of 7200mhz
(For all of this, I'm assuming you are running a 13th gen K/KF-series CPU. If it's 12th gen or non-K, the problem is bigger.)
There are a number of problems here. First, combining memory kits is generally not recommended for XMP overclocking. Even if they are nominally the same part number, they are not validated / tested to work together as a single kit. Small differences in the silicon can make nominally identical parts incompatible or sub-optimal for overclocking.
Second, although your FF3D532G7200HC34ADC01 is on the Maximus Z790 Hero Memory QVL, it is only listed for 1 and 2 DIMM configs (that's the "1,2" in the "socket support" column). 4 DIMM configs are significantly harder to overclock than 2 DIMM, and it's more or less impossible to run 4 DIMMs at the highest speeds. The fastest 4 DIMM configs on the QVL are currently 6000 (there is one at 6200, but that's clearly pushing the extremes for DDR5 in a 4 DIMM config, as there's only one at that speed). There are also no Team Group parts listed for a 4 DIMM config; which could either mean they have just not yet been tested/validated, or it could suggest there's a problem running their DIMMs in a 4 DIMM config.
Your RAM is not 7200 MHz. It is 7200 MT/s, which is 3600 MHz; but that's an overclocked speed. It's Double Data Rate, so the clock speed is half the transfer rate. The reported 2400 MHz is running at 4800 MT/s (so DDR5-4800, which is the common default JEDEC speed and the speed your silicon is designed/validated to run at by SK Hynix). XMP 7200 is an overclocked speed significantly higher than the rated speed of the silicon.
You have a fair chance of getting it to run and be stable with a moderate overclock, but very little chance of getting close to 7200 in a 4 DIMM config. You could start with enabling XMP (to load the sub-timings from the XMP profile), but then reducing the speed. I'd suggest stepping up to 5200, then 5600, then 6000; and see if it will at least boot and basically run. Once you think you have a stable speed, you need to leave it running MemTest or whatever memory soak/stress tester you prefer, for a LONG time (many hours), to confirm it's actually stable for normal gaming/enthusiast use.
If you have problems achieving those moderate clocks, try loosening the sub-timings (raising the numbers). Your part is listed as 34-42-42-84 for the sub-timings. The parts listed for 4 DIMMs at 6000 have 40-40-40-76 and 32-38-38-96 as their common theme. That gives you some idea of timings that have been known to work with SK Hynix silicon, and it's up to you to play around with them to see what works for your particular memory chips.
In general, you can't have both the highest speed and the highest capacity. That was also the case for DDR4. You can have 2 DIMMs at the super-fast overclocked speeds, but 4 DIMMs generally only runs with a more moderate overclock.