Buttons in Libreoffice flicker when hovered over

I am having an issue with LibreWriter 6.1.4. Whenever I hover my mouse of any the buttons in the toolbar, the hovered over button's outline starts flickering constantly until the button is click on with the left or right mouse button. I have tested the buttons out with OpenGL and hardware acceleration both on and off and the issue persists through both. I have also tried different GTK themes and the issue persists through all of them.

This issue seems to be similar to this issue posted a few years ago: Why are LibreOffice 5.2 menus flickering in Xubuntu 16.04?

I am using Kubuntu with KDE and a nVidia graphics card.

Any help would be appreciated. Thanks.

EDIT: Inxi output:

System:    Host: Linux-PC Kernel: 4.19.0-041900-generic x86_64 bits: 64 compiler: gcc v: 8.2.0 
           Desktop: KDE Plasma 5.14.5 Distro: Ubuntu 18.10 (Cosmic Cuttlefish) 

Machine:   Type: Desktop Mobo: MSI model: B150 GAMING M3 (MS-7978) v: 2.0 serial: <filter> 
           UEFI: American Megatrends v: B.50 date: 02/23/2016 

CPU:       Topology: Quad Core model: Intel Core i7-6700K bits: 64 type: MT MCP arch: Skylake-S rev: 3 
           L2 cache: 8192 KiB 
           flags: lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx bogomips: 64128 
           Speed: 4164 MHz min/max: 800/4200 MHz Core speeds (MHz): 1: 4139 2: 4002 3: 4075 4: 4005 5: 4112 
           6: 4134 7: 4074 8: 4062 

Graphics:  Device-1: NVIDIA GP102 [GeForce GTX 1080 Ti] driver: nvidia v: 415.27 bus ID: 01:00.0 
           Display: x11 server: X.Org 1.20.1 driver: nvidia resolution: 1920x1080~60Hz 
           OpenGL: renderer: GeForce GTX 1080 Ti/PCIe/SSE2 v: 4.6.0 NVIDIA 415.27 direct render: Yes 

Audio:     Device-1: Intel 100 Series/C230 Series Family HD Audio driver: snd_hda_intel v: kernel 
           bus ID: 00:1f.3 
           Device-2: NVIDIA GP102 HDMI Audio driver: snd_hda_intel v: kernel bus ID: 01:00.1 
           Device-3: Logitech type: USB driver: snd-usb-audio,uvcvideo bus ID: 1-5:8 
           Sound Server: ALSA v: k4.19.0-041900-generic 

Network:   Device-1: D-Link System DGE-528T Gigabit Ethernet Adapter driver: r8169 v: kernel port: d000 
           bus ID: 04:01.0 
           IF: enp4s1 state: down mac: <filter> 
           Device-2: Qualcomm Atheros Killer E2400 Gigabit Ethernet driver: alx v: kernel port: c000 
           bus ID: 05:00.0 
           IF: enp5s0 state: up speed: 1000 Mbps duplex: full mac: <filter> 
           IF-ID-1: vpn0 state: down mac: N/A 

Drives:    Local Storage: total: 4.19 TiB used: 1.39 TiB (33.1%) 
           ID-1: /dev/sda vendor: Western Digital model: WD40EFRX-68N32N0 size: 3.64 TiB temp: 23 C 
           ID-2: /dev/sdb vendor: Kingston model: SV300S37A240G size: 223.57 GiB temp: 22 C 
           ID-3: /dev/sdc vendor: SanDisk model: SDSSDX120GG25 size: 111.79 GiB temp: 22 C 
           ID-4: /dev/sdd vendor: Western Digital model: WD2500AAJS-65B4A0 size: 232.89 GiB temp: 25 C 

Partition: ID-1: / size: 42.52 GiB used: 19.07 GiB (44.8%) fs: ext4 dev: /dev/sdb5 
           ID-2: /home size: 107.49 GiB used: 68.67 GiB (63.9%) fs: ext4 dev: /dev/sdb6 
           ID-3: swap-1 size: 15.83 GiB used: 195.9 MiB (1.2%) fs: swap dev: /dev/sdb3 
Sensors:   System Temperatures: cpu: 29.0 C mobo: N/A gpu: nvidia temp: 45 C 
           Fan Speeds (RPM): N/A gpu: nvidia fan: 0% 

Info:      Processes: 341 Uptime: 4d 10h 47m Memory: 15.61 GiB used: 7.12 GiB (45.6%) Init: systemd runlevel: 5 
           Compilers: gcc: 8.2.0 Shell: bash v: 4.4.19 inxi: 3.0.24