I really wanted Solus Plasma to work for me again on my 2nd Alienware M15x laptop.
However, since recently re-installing multiple times I kept having issues.
Therefore, first thing this morning I installed Solus Budgie instead, ran updates, installed the LTS kernel, then Nvidia drivers.
All is smooth again on this machine.

Thanks all for your help, hearing me out, and advice, especially @Justin

For some reason Plasma no longer works for my hardware, but least I am still on Solus, and I love Budgie.
Now I have Budgies! 😃

@Justin check this out:
I tried again with Solus Plasma on another machine, my Dell Optiplex 755 PC.
It's an older machine, but least proves that the Plasma install does indeed still work fine.
Hoping to buy a new desktop this year.

peter@davie ~ $ inxi -Fz
System: Host: davie Kernel: 4.20.10-111.current x86_64 bits: 64 Desktop: KDE Plasma 5.14.5 Distro: Solus 3.9999
Machine: Type: Desktop System: Dell product: OptiPlex 755 v: N/A serial: <filter>
Mobo: Dell model: 0DR845 serial: <filter> BIOS: Dell v: A22 date: 06/11/2012
CPU: Topology: Dual Core model: Intel Core2 Duo E6550 bits: 64 type: MCP L2 cache: 4096 KiB
Speed: 1997 MHz min/max: 2000/2333 MHz Core speeds (MHz): 1: 2135 2: 2000
Graphics: Device-1: Advanced Micro Devices [AMD/ATI] RV610 [Radeon HD 2400 PRO] driver: radeon v: kernel
Display: x11 server: X.Org 1.20.3 driver: ati,radeon unloaded: fbdev,modesetting,vesa resolution: 1920x1080~60Hz
OpenGL: renderer: AMD RV610 (DRM 2.50.0 / 4.20.10-111.current LLVM 7.0.0) v: 3.3 Mesa 18.3.3
Audio: Device-1: Intel 82801I HD Audio driver: snd_hda_intel
Device-2: Logitech Webcam Pro 9000 type: USB driver: snd-usb-audio,uvcvideo
Sound Server: ALSA v: k4.20.10-111.current
Network: Device-1: Intel 82566DM-2 Gigabit Network driver: e1000e
IF: enp0s25 state: up speed: 1000 Mbps duplex: full mac: <filter>
Device-2: Qualcomm Atheros AR5212/5213/2414 Wireless Network Adapter driver: ath5k
IF: wlp3s0 state: down mac: <filter>
Drives: Local Storage: total: 465.76 GiB used: 6.40 GiB (1.4%)
ID-1: /dev/sda vendor: Hitachi model: HDS721050CLA662 size: 465.76 GiB
Partition: ID-1: / size: 146.65 GiB used: 6.40 GiB (4.4%) fs: ext4 dev: /dev/sda2
Sensors: System Temperatures: cpu: 43.0 C mobo: N/A gpu: radeon temp: 73 C
Fan Speeds (RPM): N/A
Info: Processes: 144 Uptime: 13m Memory: 5.70 GiB used: 1.05 GiB (18.5%) Shell: bash inxi: 3.0.32

Plus, no issues with udev and the current kernel.