Sorry that you cannot preview your panoramas while zooming in to 1:1 and 1:2 in Lightroom Classic CC 7.3.
Could you please provide a screenshot of how they look in the fit view vs the 1:1/1:2 zoom?
Also, please take a look at the solution in this discussion Lightroom Classic CC won't render photos in library view and let us know if that helps.
This is a 5-month-old bug that Adobe has chosen to not fix yet. Please add details of your symptoms to the bug report: Lightroom Classic: Preview size limit | Photoshop Family Customer Community . Be sure to click Me Too in the upper-right corner.
I have the same issue. It has been happening for quite a while now and it is annoying. It never used to happen in earlier versions of LR.
Which version of Lightroom and which operating system do you use?
Windows 10. Currently on Lightroom Classic CC 7.5.
Lightroom Classic version: 7.5 [ 1186149 ]
License: Creative Cloud
Language setting: en
Operating system: Windows 10 - Home Premium Edition
Application architecture: x64
System architecture: x64
Logical processor count: 4
Processor speed: 3.3 GHz
Built-in memory: 16327.2 MB
Real memory available to Lightroom: 16327.2 MB
Real memory used by Lightroom: 5157.9 MB (31.5%)
Virtual memory used by Lightroom: 5277.6 MB
GDI objects count: 739
USER objects count: 2559
Process handles count: 2797
Memory cache size: 145.8MB
Internal Camera Raw revision: 1001
Maximum thread count used by Camera Raw: 3
Camera Raw SIMD optimization: SSE2,AVX,AVX2
Camera Raw virtual memory: 2411MB / 8163MB (29%)
Camera Raw real memory: 2414MB / 16327MB (14%)
System DPI setting: 96 DPI
Desktop composition enabled: Yes
Displays: 1) 1920x1200
Input types: Multitouch: No, Integrated touch: No, Integrated pen: No, External touch: No, External pen: No, Keyboard: No
Graphics Processor Info:
DirectX: AMD Radeon (TM) R9 380 Series (23.20.15017.3010)
Turning the GPU on or off makes no difference.